Rubber Band Transmission

This is one of my entries in the #MakerEdChallenge. This project would help children understand the basics of speed reduction/increasing. The drive power is from a rubber band that runs the pulleys. Students can change the ratio and spin the drive shaft to watch the other spin at the ratio of the pulleys. 1st "gear" is 1:2 2nd is 1:1 and 3rd is 2:1 ratio. this is a simple educational toy so i tried to keep the parts at a minimum.

you will need to print:
2 stop_collar
2 transmission_drive_pulley
2 bracket

It doesn't cost much to print this but you will need these other things:

2 2 1/2 inch long 1/4 in dia. dowels for the axle shafts

1 rubber band that is tight enough on the pulleys.