Summary

My steppers have machined pulleys fixed on them so the normal couplings do not fit. These fit perfectly.

Instructions

My steppers have machined pulleys fixed on them for HTD 3M belt. I cannot seem to get the pulleys off. The pulleys have a length of 14.5mm, but the teeth only go untill 10,5 mm.The pulleys have a diameter of 9.7mm with 11 teeth and a 3mm pitch.

You'll need to print both halves twice, the halves are not the same. I could not make them the same because with 11 theeth i needed a mirrored cavity.
Furthermore you will need 8 m4 x 10mm screws and 8 m4 nuts.

If you als have steppers with these pulleys you might also like http://www.thingiverse.com/thing:51618 , an Y bracket you can use when your belt runs close to your stepper

Prusa 2 Z-Coupling for pulleys