Parametric LM8UU Y Stage Holder

I made this when I couldn't find a suitable LM8UU replacement for these bushings on the Y-plate: http://www.thingiverse.com/thing:8282

So I took GregFrost's LM8UU holder and added tabs with screw cutouts so that I could mount it using the current holes. However, I made it parametric so that users could adjust it for whatever width / size screw required.

There are also slots for zip-ties so they don't interfere with mounting.