XY Bracket Replacement for Robo3D R2 Printer

My R2 seems to be really hard on the XY Brackets. 3 have cracked already and new clam shells from Robo3D sometime break off tabs while installing.

Robo3D Technical Supports tells me that they no longer have any XY Brackets and will not be getting anymore.

I down-loaded the "R2 C2 Screw Together Brackets.stl" from the Robo3d Community
http://community.robo3d.com/index.php?threads/r2-c2-linear-rail-bracket-ends.19536/

I modified the design to recess the screws into the bracket because