FT5 X redesign - linear rail under extrusion

This a partial remix of my adjustable Y carriages. On a whim I decided to try putting the linear rail under the extruded aluminum putting the rail closer to the hotend (possibly making it more stable).

This is a work in progress, as I am still not happy with the part cooling fan.

The bottom half of the x carriage was built for a titan aero, volcano, bl touch, and 50mm radial fan.