"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