The middle_piece of the 3d printed shoulder rig can be quite hard to print on smaller printers like the Thing-o-Matic. (I printed the original rig on a RepMan.) It's long cross-section may induce warping and it streches the limites of the build-platform.This one is more compact. It works for the center-support of the camera-plate, the counter-weight and the follow-focus. 2 additional holes in the shape of an M5 nut in the camera_place may be required to use this as the front and back middle_piece to support that camera_plate with the compact middle_pieces as well.Blog post: http://marcuswolschon.blogspot.com/2011/07/compact-middlepiece-for-3d-printed.html