What you need, mechanically, to use motors to make something move:
- How to connect an output shaft to a motor
- How to mount a gear or sprocket to a shaft
- How to retain a shaft
- How to mount a motor to power gears or sprockets
- How to mount (and retain) wheels and rollers to shafts / gears / sprockets
I found that, without someone who already has mechanical expertise, the jump from theory to implementation is a huge stumbling block. The fabrication can usually be looked up once you know the design. But coming up with that design (the HOW of your overall design) is an often overlooked challenge.