I borrowed a friend's pipe bender, but it was only for 0.5" diameter tubes. The smallest I found at Lowe's was some so-called half inch copper colored conduit. Being impatient, that's what I bought. The diameter was really about 0.65". Being crafty, I figured I could make it work, and kept the tubing.
I determined that I could flip the bending lever around, and then 3D print parts for larger pipe. I successfully did this, and it looked like it would work.
But upon trying, the first thing to bend was the solid pin going through the middle of the circular portion of the tube bender. Darn cantilevering.
I strongly suspect I ended up not buying pure copper pipe, as that should be soft. At least my friend wasn't annoyed, merely surprised.