I just have changed the parameters of the beautiful parametric thumbwheel by 67restomodder:

http://www.thingiverse.com/thing:13807

The default parameters are for M3 nuts. In addition I have cleaned a little bit the code and changed the shape of the cutouts.

More information (In spanish):
http://www.iearobotics.com/wiki/index.php?title=Objeto_3D:_Ruedecilla_con_tuerca

• Print 8 of them
• Embed the M3 nuts
• Use on your Prusa2!!