I bought a 2nd hand test tube last year in winter and I've been having some fun on it, but now I want to wear a springsuit but the material of the rails is so sharp, it's really painful after 30 mins. I've tried to cut the sharp bits off with a razor blade, and put some wax on it, but it's not making a difference.
Any suggestions on how to make it smoother? Would gorilla tape or clear duct tape be a good option?
Photo for reference

Thanks so much!