Should become a Tire, printed in Filaflex. I designed it to fit UP! Filamentspools. The Up spool-design allows to 3d-print anker possibilities in order too create axle driven wheels. Depending on wich percentage of infill is used, the tire 's density can be regulated. Follow us on twitter; https://twitter.com/3DPrintersVDB Like us on facebook: https://www.facebook.com/3DprintersVDBWhat to do with empty spools of filament? They have a center and two sides, just like rims.. So lets make some wheels. Make sure you design the inner ring not too tight. Remember, the tire has to stay in place on the rim, but has to be fitted too. Tip; start with the filamentspool's outer diameter and inner width of the spool. Start calculating from there on. And remember that radius is half the diameter :)