Working with round tubing, especially bending it, requires marking a line around the tube so the tangent points of the bend can be seen while setting it up in the bender. This is a marking jig I built quite a while ago for doing that.
A piece of 2 x 6 and four poly casters from Harbor Freight.
Once the layout is done I just spin the tube on the casters holding the marker by hand or in a holder I built.
Not the best photo but here you can see the marked line being used to set the tangent for the bend.
These are 1" diameter x .083 wall DOM. I am building a couple of "Hot Rod Wagons" and these are the main frame rails for them.