3D Printer 3xLM8UU Minimal X Carriage (with symmetric/balanced tensioning mechanism) [#SCOUTcorexy design]

####Update: I have managed to re-do the X carriage to re-gain the lost bearing due to space constraints. Rather than updating this Thing I'll leave it as is and create a new thing altogether to reflect the new design. Here's the link: http://www.thingiverse.com/thing:1566017

Update: Added a Smartrapcore-compatible 30mm distance between belts STL, as requested on reprap forums. It is still compatible with the DualHotends Mount that I develop for SCOUTcorexy (https://www.thingiverse.com/thing:1487375/).

This is a WIP X Carriage that implements, like its predecessor, an internal belt gripping system and adds to it in functionality with a belt tensioning system that is very simple yet accomplishes a balanced tensioning that is lacking from most CoreXY printers. It uses F698ZZ bearings for belt routing for both XY and Z subsystems.

NOTE: please runt it through a STL cleaning service like netfabb.
Check it @Sketchfab: http://is.gd/ssdbmH

I have re-designed the previous Smartrapcore-compatible X carriage because in my 3D printer design build I can't add anywhere a tensioning mechanism around the belt loop so the X carriage remained the last option. I didn't really wanted to add weight with more bolts/nuts but so far it's the only option.

A unintended consequence is that by printing all those holes inside the part it becomes sturdier.

I haven't printed this one and I suspect it will need some tweaking for the sliding function to go smoothly so please do some testing if interested and report back so I update the design/info/etc. I will modify it according to the reports I get.

Please ask questions if you have any, I will try to respond to every single one of them.
You might also be interested in the 3D printer I am designing this X Carriage for: http://www.thingiverse.com/thing:1487375 (View it in 3D @Sketchfab: http://is.gd/1l27lz)

Regards.