Smartrapcore Alu - Rear L & R pulley holders/y rod supports fully supported

These are the rear pulley holders for a smartrapcore alu printer. On the suggestion of some contributors to Reprap forum, I have remixed these originally from the parts by Smartfriendz but incorporating my strengthening modifications to prevent splitting of the original parts under belt tension. Now a fully supported pulley, this prevents twisting under belt tension by adding to the rigidity to the pulleys. It should prolong the life of this part also, which is under constant belt tension and th