Hi everyone, I'm new to this site, so if I'm breaking any rules let me know. In particular because this is for my job. The forum rules seem very clear on the guidelines for homework for school and one can assume that personal hobbyist type questions aren't an issue but i don't see anything when it comes to work related queries. I've run into a problem in which i have a few (3) concentric tubes with an irregular cross section (though the same as each other). Due to machining tolerances we're stuck with a small gap, mechanically it doesn't matter but perspective isn't so good as someone can easily shake the central tube making it look unstable. I've tried finding a material to fit into the gap (Teflon, cork, PTFE, various tapes, cabinet bumpers etc.) but every item i've tried either creates too much friction or will not endure the movement of the tubes (often the adhesion gives). I feel that i must not be alone in this problem as there is so many items out there with concentric tubing. How do they solve the problem?