I made this tubing cutter for cutting aquarium tubing and bowden tubes. I like several of the designs that are out there, but I didn't like that many of them use screws and springs that you have to source and assemble. This one is a single piece that just guides the blade. It uses standard single edged blades like you find in scrapers (i.e. not a razor knife or box cutter). It's also got a V shaped anvil so that you can use it on multiple diameters of tubing. Be careful with razor blades!

Print and profit.

Attribution - Creative Commons