I wanted a webcam arm that was taller than the ones I could find. There are three lengths of thumb screws. The long one is for the base link, the medium for all of the other arm links and the "tightening" version for holding the camera to the mount. They are all 1/4 - 20, so you could substitute a metal version.

I used a tap and die for the threads after printing because mine were too tight straight off the printer. Alternatively, you could shrink the diameter of the thumb bolts a little.