One potential problem I see with the manufacture is how do you get the roller assembly inside the outer-sleeve?
Forcing it in with a hydraulic press could cause latitudinal slippage of the belting on the rollers.
The outer-sleeve could be formed by sticking two halves together around the roller assembly, but that leaves two seams as potential weak points--depending on material. Could make replacing belting troublesome--sleeve cut apart, belt(s) replaced, and joined together again.
Perhaps a water based lubricant, like methylcellulose, could be used in conjunction with a hydraulic press to get it in there. Then the lubricant would be flushed out.
