I have been working more on some 3D models for drills that I will have in the game. The premise is this. The player starts out with a simple drill. It can mine copper and iron ore, however it is quite slow because it overheats quickly and also requires recharging often. The player can upgrade three parts of the drill to improve it. First they can upgrade the energy capacity so the drill can be used for longer without needing more energy to run. Or they can upgrade the cooling which means the drill will not overheat in the middle of drilling as often. Or they can upgrade the drill head, which can improve other aspects such as the amount of material you get per ore.