I make a lot of projects that use 3/8" aluminum tubing and one of the things I hate is that it is sold on 50ft. rolls. Which doesn't help much if you need straight pieces. So I made this roller to be part of a 3D printed tubing straightner. However, the base undured too much strees and flexed too much to make a usable tool. So I wound up using a piece of 3/4" plywood. This works better than anything that I have tried up to this point. It still leaves an ever so slight arc in a 3ft piece of tubing, but it can easily be worked out by hand, or by rotating the tubing in the rollers while you move it back an forth.This roller can also be used for other 3/8" tubing and rod projects, so I decided to put it on Thingiverse to see what others make of it.To make a tubing straightner:Print out 3 rollers. Be sure to clean out loose plastic in the bottom beariung hole. I use needle nose pliers and a flat head screw driver. There may be a better way to print this so that the plastic does not ooze down there while the roller is printed, but I am new to 3D printing and this is only my second custom made print.Press in the bearings. The rollers are designed to use 3/4" x 25" roller skate bearings. I pressed each bearing in with a bench vise. Tap it in with a hammer should work if you don't have a bench vise.