Years ago I got tired of searching for a cheater pipe when the need arose. Usually, I had not done enough planning ahead. The solution was to build a variety of these tools and organize them so they were handy. The organization was just a matter of attaching a hanger and spraying on some paint so their application was easily recognizable. Yellow & red is sprayed on the hot end and green on the cold end.
I didn’t give enough thought to attaching the first hangers and just welded a ring on the end of the pipe. It then became apparent that the hanger limited the use of the pipe - it couldn’t slide all the way down a long workpiece. This is important when the radius of the bend must be tight. For me, the ring needs to be attached on the side of the pipe leaving the end unobstructed.
I tend to distinguish between cheater pipes (hollow) and cheater bars (solid) but apparently some people use “bar” for both types of torque multipliers.
There is a pretty good discussion of the theory and use of cheaters on Wikipedia.