Cotton Reel Racer.

A 3d printed version of a cotton reel racer or cotton reel tractor. I played with these when I was a kid and so I thought I'd make a printable version. Good fun for the kids or as a desktop toy for you. Assembly is easy enough. Just thread a rubber band through the center hole and around the locking bar at one end and through the washer and around the main bar at the other end. I used a thin length of wire with a small hook at one end to pull the band through. You will have to experiment with the size and strength of the rubber band. If it is too powerful the reel will spin and jump around without going forward, too weak and it wont move at all. Try to find one that will let you wind lots of turns but still give a smooth output. I found that a small thin band was best. I printed mine at 0.2mm layers, 3 perimeters and 15% infill. No support is needed.