I’ve seen it done by just adding a straight stud out the end of the center of the roller on each side. A big bolt with some big washers on the end would work in the case of a propane cylinder.
Then just tie a rope to each stud. The “bearing” is the knot looped around the stud. Friction isn’t really an issue at slow rolling speeds.
You need to add a “spreader” to keep the Y of the rope far enough apart so it doesn’t rub on the leading edge of the roller. Hopefully you see what I mean here, wish I had a quick drawing I could post.
Personally, I’m using a lawn roller I borrowed from my neighbor. I borrowed it and then he said hey you know that lawn roller that you borrowed? Yeah, don’t bring it back, it was just cluttering up my shed and I like it better now that it’s gone. It’s not the heaviest roller but fill it completely full and it does the job of getting good seed contact to the soil and I’m sure it also prevents some mositure loss.
Grouse