Aluminum will not work. Where are you located? You can’t order something online 23.5, 25, or 25.4mm? Me or maybe someone closer could mail you conduit if you can’t find it online.
A customizer is out of the question. Every single part changes with the rail size, as well as moving mass, and hardware length. The amount of under sizing depends on the size of the rail as well. If the design strayed too far, new electronics would be needed.