Y Carriage Mounting Frame for Slim LM8UU Holders

It's a quick solution to avoid manual aligning of the slim LM8UU holders underneath your y carriage.

Like for my x carriage (http://www.thingiverse.com/thing:18657) I changed the "body_wall_thickness" from 2mm to 3mm, which gives quite durable results.

You won't save any screws using this part so far, but you will experience a much more comfortable assembly during your printer build. I didn't even drill a single hole through the wooden sheet for my y carriage but simply used short wood scr