"Smartrap CoreXY"-like X Carriage with internal clamping belts (gets rid of the "in-the-way" belt clamping ears)")

See in 3D how this X Carriage is going to be included into the [WIP!] 3D printer I am designing, at Sketchfab: https://skfb.ly/LPP7

WARNING: THIS "THING" IS NOT INTENDED TO BE PRODUCTION READY!! Download and modify to suit your needs.

###__ NOTE:__ The solution I will go forward with has been chosen, namely the printed internal teeth. You can find the latest iteration of the design at http://www.thingiverse.com/thing:1505842, where I have added a tensioning system to the "earless" feature. You can see the first iteration here ("earless" only): http://www.thingiverse.com/thing:1369402

I wanted to start somewhere in designing a CoreXY 3D printer and SmartRap core was one highly debated at the time for its JSCAD customizer and its rapid growth. So I downloaded the package and tried to add a dual hotend, which I failed because of those ears that "catch" the belt. They also seem feeble to me and unaesthetic. Difficult to package maybe. Or I simply didn't like it just because.

I set myself on a journey to achieve a similar X carriage (for vertically stacked X rods) but better (better for me that is).

Currently I have 3 solutions that I am currently printing test parts of so I can decide which one is the easiest to print, easiest to clamp and maybe even tension.

For the first solution I have designed a toothed surface against which the belt would be gripped inside the X Carriage block simply by inserting it through the slot at the wider gap level and sliding it down or up in between the 3D printed teeth.

The second and third solutions are based on several designs I have seen online or that have been pointed to me on reprap forums (especially this one on youmagine: https://www.youmagine.com/designs/gt2-belt-clamps).

They are basically using the belt's own teeth to clamp itself by routing it around another pin or round object.

This will be updated as I achieve more results/ have more ideas.

Update 2016/02/25: Please check http://www.thingiverse.com/thing:1369402 for the STL of the X Carriage I've chosen.

Update 2016/01/31: I have realized that on a CoreXY all belts always face the same direction so I have re-designed the whole thing and updated all the files here. The third solution was not suitable anymore so I have deleted it. I have uploaded two small printable parts that can be fiddled with in a CAD software to modify the distance between the teeth and the walls and also the teeth depth so that you can print it until you get a good result for belt grip. Then you can print the whole carriage (which is not uploaded yet).