@CrazyN

3D Flappy brings the classic arcade challenge into a full 3D space, where you guide your blocky voxel bird through an endless obstacle course of green pipes. Simply press Space to flap your wings, dodge as many barriers as you can, and set a high score. A huge shoutout and massive thanks to One Minute Games for the awesome inspiration behind this project. Watching their content sparked the idea to build this game in Unity, and following along with those mechanics made the whole game development journey so much fun. I could not have brought this pipe dodging game to life without that initial push.

The Floating Bird Mystery

What I was trying to do: Build a space-themed Flappy Bird game in Unity.

The Problem: When I tried to make the bird fall toward the ground, it kept flying upward or disappearing off-screen.

How I fixed it:

Checked my animations to ensure position keys were not overriding movement.

Discovered the player GameObject was marked as Static, preventing Unity’s physics from moving it properly.

Reset the player’s Mass from around 184 down to 1 so gravity wouldn’t shoot it out of view.

Turned off Apply Root Motion on the Animator component.

Input System & Collision Setup

The Problem: A red console error appeared regarding UnityEngine.Input, and the bird was flying straight through obstacles without hitting anything.

How I fixed it:

Fixed the Unity Input setting by allowing Both old and new input handling systems in Project Settings.

Located the Gizmos toggles in Unity 6 to inspect collider wireframes.

Realized my project is set up in 3D, so I needed to convert the bird’s physics components from 2D (Rigidbody 2D, Circle Collider 2D) over to 3D (Rigidbody, Box/Sphere Collider).

Pipe Collisions & Physics Overrides

The Problem: The bird was passing directly through the pipes instead of crashing or triggering a game restart.

How I fixed it:

Identified that my C# script was moving the bird by directly modifying transform.position, which bypassed standard physics collisions.

Set Is Trigger on the Pipe colliders so OnTriggerEnter would register hits.

Added a 3D Rigidbody to the Bird to ensure the physics engine tracks trigger events.

Pipe Spawning & Floor Obstructions

The Problem: When spawning pipes at random Y heights, their colliders were physically catching on the Floor object, blocking them from reaching the bird.

How I fixed it:

Enabled Is Trigger on the Floor’s collider (or isolated layers) so pipes pass cleanly through the ground regardless of spawn height.

Restructured the pipe hierarchy and spawning script to instantiate pipe prefabs cleanly in 3D space at Z = 0.

I decided to make a 3D version of Flappy Bird since I believe that there is more thrill to that than the original one

Just imagine playing the classic game of Flappy Bird, but it is Space. I made a Space version of flappy bird where you can only control stuff with the spacebar.

Here’s the current progress:

For my BumperGoals GitHub repository, I completely overhauled the documentation and presentation to match a professional engineering standard.

First, I fixed the overall layout of the repository’s landing page by completely replacing the basic documentation with a beautifully formatted README file. I added interactive badges at the top, including direct simulation links to both Wokwi project pages so anyone visiting can immediately test out the code and circuits for the robot chassis and the controller.

Second, I integrated high-quality visual renders directly into the documentation. I structured the file to cleanly display my design images side-by-side, perfectly matching the controller shell and its corresponding PCB board layout, as well as the main robot chassis design and the motor assembly view.

Third, I cleaned up and corrected the technical data. I mapped out the exact pin configurations for the dual joysticks and the Arduino Nano into an easy-to-read hardware pin table. I also corrected and clarified the movement logic matrix to clearly show how the mirrored N20 motors handle tank steering when pushing the left joystick for straight lines and the right joystick for sharp spins.

Finally, I added a clear, step-by-step assembly section detailing exactly how to construct both the handheld controller and the robot chassis, ensuring that the repository serves as a complete, production-ready guide for building the physical hardware from scratch.

For my BumperGoals project, I have successfully finished all of the virtual prototyping, firmware validation, and repository documentation.

First, I designed the system architecture for a tabletop robotic soccer game involving a 2v2 match setup. I planned out custom wireless controllers that feature ergonomic shells, joysticks, microchips, and battery power boosters to talk directly to the mini bumper car chassis.

Second, I mastered the differential steering logic. Because the N20 gearmotors are physically mirrored on opposite sides of the chassis, I created a custom tank-drive control matrix to handle their directions perfectly. I successfully implemented logic matching my precise controller criteria: pushing the left joystick up or down moves both wheels forward or backward, while pushing the right joystick left or right executes instant, high-speed tank turns.

Third, I completely validated my code and wire layouts using the virtual simulator. I wired a virtual Arduino Nano layout to indicator LEDs representing the motor driver outputs. By running an automated script, I successfully proved that my firmware and PWM-capable pin routings function exactly as intended.

Finally, I finalized production-ready documentation for my repository. I wrote a clean README file that captures the project summary, includes interactive simulation badges, links layout images like Controller.png and Robot.png, maps out the pin configurations, and provides a step-by-step assembly guide for when I am ready to build the physical hardware.

I upgraded my project from a large Arduino Uno to a compact Type-C Arduino Nano so it could fit inside my handheld controller case.
I set up the circuit simulation in Wokwi and wired up two analog joysticks to my Nano across pins A0, A1, A2, and A3. When I ran into compilation errors caused by a typo with brackets on a serial print line, I cleaned up the code. I also noticed that moving my joysticks gave inverted reading values, so I map-tested the directions to ensure the logic was solid.
I then designed a specific tank-steering driving logic to handle how my two wheels spin relative to each other for forward, backward, left, and right movements, keeping in mind that the motors face opposite directions on the chassis.
Finally, I categorized my 3D design files into the controller top shell, the chassis base, the full robot frame, and the gearbox drivetrain setup, and packed everything into a comprehensive README file for my GitHub repository.

I upgraded my project from a bulky Arduino Uno to a tiny Type-C Arduino Nano so it would actually fit inside my custom handheld controller case.

I set up a virtual circuit in Wokwi and wired up two analog joysticks to my Nano, mapping them across pins A0 through A3. When my code wouldn’t compile because of a few stray brackets on a print line, I fixed the typo. Then, when I ran the simulation and realized my joystick inputs were completely inverted and reading on the wrong axes, I wrote a troubleshooting script to see exactly how the hardware was reading my hand movements.

I also went through my 3D design files and identified each of my CAD models, figuring out exactly which ones were the controller top shell, the chassis base, the full robot assembly, and the drivetrain gear setup.

Finally, I pulled everything together—my code, wiring schematics, building instructions, CAD images, and an interactive PCB badge—and wrote one master README file for my GitHub repository so anyone checking out my profile can see exactly how I built it.

Hi! I made a cool engineering project where you build a tabletop robotic soccer game called Bumper Goals, where two teams of custom-made mini bumper cars face off in a fast 2v2 match to be the first to score five goals. To control the cars, you are designing a bunch of custom, easy-to-hold controllers that have built-in screw holes, clean cutouts for the joysticks, and a top shell that snaps tightly onto the bottom plate. Inside the case, each controller uses a tiny computer chip, a power booster to keep everything running smoothly on regular AA batteries, a simple power switch, and a wireless chip to talk to the robots. By writing your own code and uploading it using a plug-in hardware programmer, you are creating a completely wireless, real-life arcade game from scratch.

This budget spreadsheet breaks down the total cost to build multiple units of both the bumper car robots and their controllers, split into mechanical parts and wiring components.Here is the breakdown of how the numbers add up:
Bumper Car Expenses
The robot mechanical section totals 216.92 dollars. This includes 4 ball casters for 21.96 dollars, 8 micro metal gearmotors for 183.60 dollars, and 4 dual-AA battery holders for 11.36 dollars.
The robot wiring section totals 247.28 dollars. This covers 8 Baby Orangutan B-328 microcontrollers for 183.60 dollars, 1 USB AVR programmer for 17.95 dollars, a 4-pack of Tattu batteries for 29.99 dollars, and connecting hardware for 15.74 dollars.
Controller Expenses
The controller mechanical section totals 26.66 dollars. This covers an 8-pack of the Gebildet joysticks for 9.99 dollars, a 20-pack of the slide switches for 4.99 dollars, and soldering supplies for 11.68 dollars.
The controller wiring section totals 27.80 dollars. This pays for 4 of the Pololu 5V step-up voltage regulators.Summary of TotalsWhen categorized by where you are buying the parts, you are spending 72.39 dollars on Amazon and 444.27 dollars on Pololu.
When categorized by type, the total mechanical hardware costs 243.58 dollars and the total wiring and electronics cost 275.08 dollars.
The combined subtotal for all components is 518.66 dollars. Adding a 10 percent estimated tax of 51.87 dollars brings the final grand total for the entire project setup to 570.53 dollars.

What I Have Designed And DoneThe Controller Enclosure

Top Shell: I modeled the main controller housing with a hollowed-out internal cavity, a uniform wall thickness, and integrated dual 21 mm circular joystick cutouts.

Bottom Plate: I created a 3 mm solid matching backplate featuring an interlocking, 1.5 mm high alignment lip that keys perfectly into the top shell to prevent twisting.

Mechanical Fasteners: I added four heavy-duty screw pillars inside the top shell corners with an inner diameter of 2.5 mm and an outer diameter of 5 mm. These line up perfectly with matching 3 mm clearance screw holes on the bottom plate.

Internal Component Layout
In my main assembly workspace, I have arranged the physical layouts to ensure everything will fit inside the shell:

Power Hardware: I locked a large dual-AA battery holder directly down the center channel. I also cut out a precise 10 mm by 4 mm slot on the top rim to perfectly seat my physical SS12D00 slide switch.

Left-Pocket Assembly: To keep things organized, I clustered my main electronics on the left side of the battery holder:

The Baby Orangutan B-328 microcontroller.
The nRF24L01 wireless transceiver module for robot communication.

A tiny Pololu 5V Step-Up Voltage Regulator to boost my AA battery power up to a clean 5V.

🤖 The Bumper Car Robot Build

Mechanical & Power Foundation: I completed the physical assembly of the 2-wheel differential drive setup, integrated a ball caster for stability, installed 2 motors, and wired up the battery.

Control & Wireless System: I added a wireless transceiver and an external programmer to flash code onto the robot.

Smart Hardware Choice: To save time, I skipped designing a custom PCB from scratch and chose the Baby Orangutan B-328 Robot Controller, which perfectly combines an ATmega328P microcontroller and a dual H-bridge motor driver in one compact package.

🎮 Custom Controller CAD Design (Autodesk Inventor)

Shell Geometry: I created the main gamepad faceplate and used the Shell tool to seamlessly hollow it out, establishing a uniform, clean 3D enclosure.

Joystick Integration: I spaced the thumbstick centers 3 inches apart and sized the clearance holes to 21mm to ensure full range of motion. On the inside ceiling, I successfully sketched and extruded 5mm outer / 2.5mm inner mounting bosses tailored for secure M3 screws.

Battery Cradle Optimization: After realizing a 4 AA holder was too large, I pivoted to a compact 2 AA holder (1.25 in x 2.5 in). I successfully mapped out its boundaries in the center channel and extruded a 0.30-inch-high 3D nesting cradle with 0.08-inch walls to lock it in place.

Power Switch Cutout: I oriented the workspace to view the flat back wall from the outside and used the Extrude (Cut) tool to pop a perfect rectangular slot straight through the shell for the main power switch.

Brain Placement: I moved back to the inside floor of the controller to map out the micro-mounting standoffs (0.08 in inner / 0.16 in outer circles) to keep the microcontroller safely elevated.

I transitioned my detailed 2D sketch into a solid 3D part by executing a clean extrusion of the main controller faceplate.

I discovered that the Shell tool is a much more efficient way to create uniform walls than trying to offset complex intersecting lines in a sketch.

I successfully used the Shell tool to hollow out the solid 3D block, turning it into a true lightweight controller housing with an empty internal cavity.

I set up my workspace to look directly at the inside ceiling of the empty shell and prepared to sketch the five-millimeter mounting bosses that will hold my joystick modules in place.

I perfected the joystick openings by modifying my 2D sketch to size the two thumbstick holes to exactly 21mm, ensuring my controllers will have a full range of motion without any mechanical binding.

I learned internal component layout strategies by mapping out the step-by-step logic for transforming a flat faceplate into a 3D shell, including using mounting bosses for the joysticks, building an internal cradle for the battery, and cutting precise slots for the power switch and programming ports.

I mastered the Inventor interface by navigating Autodesk Inventors Modify panel to locate the Offset tool right next to the Stretch command.

I prepped the 3D shell geometry by setting up my active workspace to transition my flat sketch into a hollowed-out 3D top housing with a strong, uniform wall thickness.

🤖 My Robot Build & Setup

My Mechanical & Power Baseline: I have successfully put together the mechanical foundation of my bumper car—finishing the 2-wheel differential drive setup, adding a ball caster for stability, installing 2 engines, and wiring up the battery.

My Control & Wireless Integration: I integrated a robot controller and a wireless transceiver to handle remote commands, and I have an external programmer ready to flash my code onto the hardware.

My Smart Component Choice: Instead of spending time designing and manufacturing my own custom PCB from scratch, I realized I can save time and effort by buying a pre-made, highly integrated board like the Baby Orangutan B-328 Robot Controller. Since it already includes an ATmega328P microcontroller and an on-board dual H-bridge motor driver in a tiny package, it perfectly fills the electronic gaps I had!

🛠️ My Hardware Ecosystem & Community Goals

Beyond the physical workbench, I explored how to scale my building skills and get involved with the community:

Hardware Super Builder: I learned about the process to apply to become a Hardware Super Builder to showcase my engineering and making skills.

The Printing Legion: I discovered the Printing Legion and how to leverage community resources/3D printing for my project.

Outpost Submissions & Stipends: I learned how to submit my hardware projects via the Outpost Design Submission form and figured out how to apply for additional Outpost travel stipends to bring my creations to events.

My Project Log: The Master Blueprint for the Micro Bumper Car

Phase 1: Mechanical Framework & Gear Mastery

I kicked off the project by designing a compact, 2x2x2-inch 3D-printed chassis featuring a main tub, a top lid, a front ball caster, and a two-wheel differential drive setup. When my Pololu N20 micro gearmotors proved too long to sit horizontally end-to-end, I pivoted to a vertical motor configuration. I used a 90-degree, 1:1 bevel gear mesh to transfer power to the wheels. To prevent the wheels from sagging and stripping the gears during intense collisions, I engineered integrated structural axle tunnels and flat-bottomed pillow-block supports to anchor the axles rigidly to the chassis floor.

Phase 2: Power Architecture & Space Optimization

To maximize my remaining internal space, I chose a flat, horizontal layout on the wide-open front deck. I selected a high-capacity 1S 3.7V LiPo battery in a compact 752540 / 802540 size footprint (about 1.57 x 0.98 inches) to act as a heavy, low-lying weight over the front caster. For reverse voltage protection, I opted for a physically keyed JST-PH 2.0 connector on the battery rather than wasting space on a massive protection circuit board. To maintain a rock-steady power supply as the battery drains, I integrated a tiny Pololu 5V buck-boost voltage regulator to feed the electronics cleanly.

Phase 3: The All-In-One Brain

To keep my electronics bay clutter-free, I selected the Pololu Baby Orangutan B-328. This tiny board solves my spacing issues by combining an ATmega328P microcontroller and a dual H-bridge motor driver on a single 1.2” x 0.7” board. Because Pololu doesn’t offer an official 3D CAD file for this legacy module, I used the engineering “block-out” method to model a basic dimensional placeholder in Autodesk Inventor, allowing me to build custom plastic mounting walls and standoffs perfectly surrounding it.

Phase 4: Programming & Wireless Strategy

For the 4-player soccer tournament, I mapped out the wire paths routing power from the battery through the regulator to the brain, and then down to the N20 motor solder tabs. To flash my custom Arduino code onto the cars, I selected the Pololu USB AVR Programmer v2.1. I cleared up a major misconception here: the programmer stays on my workbench and is only plugged into the Baby Orangutan’s 6-pin ISP header (matching up the red stripe to Pin 1) for a few seconds to upload code. I only need one single programmer to update all four tournament cars, saving weight and money.

Phase 5: Wireless Control & Custom Transmitters

To wirelessly drive the car without the signal overlapping with the other three players in a match, I ruled out messy Infrared (IR) remotes. I instead explored two secure options: standard 2.4GHz hobby RC car pistol-grip controllers paired with a micro-receiver, or Bluetooth control via smartphone apps. I also mapped out a completely custom DIY option: building my own handheld transmitter from scratch using an Arduino Nano and an analog joystick module, transmitting data through the air to the robot via paired nRF24L01 2.4GHz radio transceivers for a secure, lag-free match!

My Project Log: The Micro Bumper Car Evolution

Phase 1: Chassis and Drivetrain Layout

I started by designing a miniature bumper car body with a tight 2x2x2-inch footprint, consisting of a main chassis and a top cover plate secured by four screws. For movement, I chose a two-wheel differential drive system paired with a single front ball caster for three-point stability on the floor.

I selected a high-quality 6V, 500 RPM N20 micro gearmotor from Pololu. When I brought the CAD files into Autodesk Inventor, I quickly realized the motors were too long to sit end-to-end in a straight line inside my small chassis. I first explored a staggered layout using custom-generated imperial spur gears but ultimately found a much better solution: flipping the motors completely vertical. Using Inventor’s bevel gear generator, I engineered a compact 90-degree, 1:1 gear mesh to transfer power directly from the upright motors to the wheel axles.

Phase 2: Structural Integrity and Gear Protection

Once the layout was set, I noticed a major mechanical flaw: the wheel axles were completely unsupported, meaning the weight of the car would cause them to sag, bend, and instantly strip the fragile bevel gears. I fixed this by sketching an internal support tunnel on the chassis wall, overcoming an Inventor extrusion direction error to merge the plastic inward.

To completely eliminate the lever-arm effect on the wheels, I designed a custom, flat-bottomed support block that bridges the gap between the tunnel and the wheel hub. This pillow-block style support sits flush against the chassis floor, absorbing all driving impacts and keeping the bevel gears perfectly aligned at 90 degrees.

Phase 3: Electronics Packaging and Component Selection

With the mechanics locked down, I turned my attention to the empty space on the front deck to solve the internal packaging puzzle. I decided to maximize this room by opting for a large, high-capacity 1S LiPo battery in the standard 752540 or 802540 form factors (roughly 2x1 inches), ensuring long runtimes and a low center of gravity.

To save even more space, I selected the ultra-compact Pololu Baby Orangutan B-328, which conveniently combines a microcontroller and a dual motor driver onto a single tiny board. Because an official 3D model didn’t exist for this board, I used the engineering “block-out” method to model its exact 1.2x0.7-inch dimensions in Inventor, allowing me to successfully map out the electronics bay layout.

Phase 4: Wireless Control and Tournament Planning

Finally, I shifted focus to how a player will actually drive the robot. I mapped out the electrical paths connecting the battery to the controller, and the controller outputs to the N20 motors. To make the car fully drivable via a handheld remote, I integrated a wireless receiver into the layout.

Anticipating a 4-player bumper car soccer tournament, I analyzed potential radio interference to make sure the match wouldn’t turn into a chaotic ruckus. I ruled out cheap Infrared (IR) remotes because they blast identical light signals that would accidentally control every car at once. Instead, I established that using a digitally bound 2.4GHz RC system or paired Bluetooth modules will guarantee secure, 1-to-1 connections, allowing all four robots to compete fiercely without interfering with one another.

Project Summary: Micro Bumper Car Drivetrain Evolution:

I started by designing a miniature bumper car body with a 2x2x2-inch footprint, including a main chassis and a top cover plate secured by four screws. I set up a two-wheel differential drive system combined with a single internal front ball caster for stability, making sure the wheels and caster aligned perfectly on the floor plane.

Then, I selected a 6V, 500 RPM N20 micro gearmotor from Pololu, which has an extended rear shaft. I downloaded the official CAD files and successfully identified the correct part file to bring into my Autodesk Inventor assembly. After analyzing how the motors fit inside the tight chassis space, I realized they are too long to sit end-to-end in a straight line. I drew up a staggered layout concept with spur gears and successfully configured Inventor to generate perfectly sized micro spur gears after adjusting for imperial unit settings. To optimize space even better, I decided to pivot to a vertical motor layout where the motors stand completely upright. I used Inventor’s bevel gear generator to create a pair of tiny 90-degree gears with a perfect 1:1 ratio. I designed and made the entire internal assembly layout myself by constraining the vertical motors and interlocking the bevel gears directly to the wheel axles.

After that, I successfully imported the ball caster and modeled a dedicated, custom 3D-printable base mount platform directly on the chassis floor. Next, I realized that the wheels and axles were completely unsupported, which would cause them to sag and strip the gears under a load. I sketched an internal support tunnel on the chassis wall and overcame an extrusion direction error to successfully join the plastic inward.

Finally, I designed a custom flat-bottomed support block that connects directly to the tunnel and sits flush against the chassis floor to fully support the wheel axle, eliminate the lever arm effect, and keep my bevel gears perfectly aligned under load.

I started by designing a miniature bumper car body with a 2x2x2-inch footprint, including a main chassis and a top cover plate secured by four screws. I set up a two-wheel differential drive system combined with a single internal front ball caster for stability, making sure the wheels and caster aligned perfectly on the floor plane. Then, I selected a 6V, 500 RPM N20 micro gearmotor from Pololu, which has an extended rear shaft. I downloaded the official CAD files and successfully identified the correct part file to bring into my Autodesk Inventor assembly. After analyzing how the motors fit inside the tight chassis space, I realized they are too long to sit end-to-end in a straight line. I drew up a staggered layout concept with spur gears and successfully configured Inventor to generate perfectly sized micro spur gears after adjusting for imperial unit settings. To optimize space even better, I decided to pivot to a vertical motor layout where the motors stand completely upright. I used Inventor’s bevel gear generator to create a pair of tiny 90-degree gears with a perfect 1:1 ratio. Finally, I designed and made this entire internal assembly layout myself by constraining the vertical motors and interlocking the bevel gears directly to the wheel axles. Most recently, I successfully imported the ball caster and modeled a dedicated, custom 3D-printable base mount platform directly on the chassis floor to give it a solid structural home and complete my stable, rolling drivetrain layout.

I started by designing a miniature bumper car body with a two by two by two inch footprint including a main chassis and a top cover plate secured by four screws I set up a two wheel differential drive system combined with a single internal front ball caster for stability making sure the wheels and caster aligned perfectly on the floor plane Then I selected a six volt five hundred RPM N20 micro gearmotor from Pololu which has an extended rear shaft I downloaded the official CAD files and successfully identified the correct part file to bring into my Autodesk Inventor assembly. After analyzing how the motors fit inside the tight chassis space I realized they are too long to sit end to end in a straight line I drew up a staggered layout concept with spur gears and successfully configured Inventor to generate perfectly sized micro spur gears after adjusting for imperial unit settings. To optimize space even better I decided to pivot to a vertical motor layout where the motors stand completely upright, I used Inventor’s bevel gear generator to create a pair of tiny ninety-degree gears with a perfect one to one ratio. Finally, I designed and made this entire internal assembly layout myself by constraining the vertical motors and interlocking the bevel gears directly to the wheel axles to complete my custom high efficiency micro drivetrain.