X-Carriage for Flsun i3 with adjustable BL-Touch mount

I wasn't happy with the original original acrylic carriage. It used two widely-spaced screws to mount the hot end and they ended up bending the acrylic. (see: [http://www.thingiverse.com/thing:2172906].) While I was working on a better mounting system I also added a place to mount a part-cooling fan and an adjustable mount for the BL-Touch.

This version uses four m3 screws to mount the hot end--you need two copies of the collar part.

The BL-Touch mount was designed around m2.5 hardware al