I got tired of breaking off the fiddly grippers on Josef Prusa's Igus-bushing-compatible Y-carriage bushing holders, so I beefed them up to be simple holes more suitable for press-fit Igus bushings (which you can get at techpaladin.com). Now there's no way you'll break them, and they hold the bushings more securely, too. If you find the holes too small to fit your bushings, you may need to ream them a bit.I've uploaded the .scad files that I modified to make these parts. They may have additional dependencies, but you should be able to grab those from Josef Prusa's github at github.com/prusajr/PrusaMendel/tree/master/sourceIf you use Igus bushings, you may be interested in my Igus bushing-compatible X-carriage: http://www.thingiverse.com/thing:14530…And X-ends: http://www.thingiverse.com/thing:14494