After running into issues with missing 3D models for my components, I had to manually source STEP files from GrabCAD and assign them to their footprints in KiCad. This taught me a lot about how KiCad handles footprints and 3D models separately, and how component libraries work. I also learned the difference between standard and reverse mount components. For example, the SK6812 MINI-E is reverse mount, meaning it sits on the back of the PCB and shines through a hole toward the keycap. With all that sorted, the PCB is complete and ready for case design.