I'd like some help from builders - modellers or mechanical tinkerers. I'm trying to build the skeletons of some polyhedra - the vertices are intersections of rods - no faces. Like this. I want to be able to telescope the rods by about 3x. So, I could slide them anywhere between, say, 1" long and 3" inches long at will. One way to do it is to use a rod-and-sleeve or piston design with brass rod and hollow brass tubing that you can buy at a hobby store. Trouble with this idea is that it won't compress to one third of its length - only half at best. To do a factor of three I'd need one rod surrounded by a sleeve surrounded by another sleeve. see attached diagram It gets way more complicated when you add in mechanisms to stop the pistons from simply falling apart at full extension - they need slots and pegs, etc. I'm looking for fresh ideas on how I can get the effect I want with less building and tinkering and with more reliability so that it doesn't fall apart. Less work would be nice too. If I can start with materials that I don't have to completely craft, that'd be great. I have to make 32 of em. The rods should smoothly expand and contract by a factor of about three, yet remain rigid. It doesn't have to be overly strong, I've been toying with plastic tubing and elastic bands and stuff. Ideas?