This is a simple U-Joint library for OpenScad.
Usage is pretty simple, specify the diameter and you'll get a ujoint.
//create a ujoint with a radius of 20mm
Printed at 20mm/w a .35mm nozzle it seems to work pretty darn well. You should be able to simply print this part, and remove the support material and it will work. I printed the support material every 2mm
I've tested this with radius of 15mm-40mm and it seems to work pretty well.