MAJ 03/25/2018 : Addition of motor and built-in centerings in the design. Thickening of the structure and refining of the semi-flex part. Increase of the semi-flex surface in compensation. A more accomplished version of the low cost dampers found on the net. I adjusted the stiffness of the silent-block to be able to normally tension the Y-axis belt without sacrificing the geometry of the motor / return roller assembly. you can compare the difference on the enforcement of the geometry in the picture above. I adapted the dimensions so as not to damage the damper when tightening because of thin walls. PET EPR is perfect for this kind of technical parts, it is indeed very resistant. P.S. : If my English seems bad, thank you to address your complaints to Google Trad ';) And, I know, I draw like a kid of 4 years!