Screw threaded telescopic platform (20mm)

####Screw threaded telescopic platform, 20mm deep, 4 and 5 segment versions.

These objects are a concentric series of threaded rings, each captive within the next ring out. The rings can be screwed up or down between two end stops positioned such that all of the rings, when screwed down, line up with each other to form a disk, or screwed up so that each extends above the ring directly outside of it to form a taller, cone-like structure.

Because these rings need to be fully captive 3D printing offers the easiest approach to creating this type of structure as all of the rings can be created at the same time in their final position, which avoids having to fit/attach one of the end-stops following creation as separate pieces with subsequent assembly. Note: The 3D models are set-up to print with the upper surface flat on the print bed. This gives a better surface for adhesion but should be remembered if it becomes necessary to apply any force to free up the rings; the rings screw ou