"Yeah, I have a 31" die for 3/8" hard line"
In fact, everyone does - use the grooves on your tire to hold the line, then gently persuade it around the circumference. The rubber will give a little bit so the tube won't buckle unless you really haul on it. This is useful for following the curve on the frame rail, or in my case I used it to make up my headlight conduit:

You can see a very slight bend on the horizontal section of tube. Basically, I wanted to give it some shape so it wasn't straight.

This tip from Welder Series

Welder Series has many really nice bracket and kits Check out their website for details on all of their parts.