I have seen 3 different versions of the rollers. The early ones were a small tube like design.
The next version has a small flare on each end. The current version has a larger flare on one end.
They all melt with enough help. An aluminum washer is supposed to go between the roller and the bowl. I am thinking it is supposed to resist heat better than say a steel washer. It would probably work if it was a bit thicker and larger. Since a lot of people tend ot put too much charcoal and bank it directly against the side that has the bale, melting is inevitable.
Someone who has access to a machine shop could fashion one from a solid piece of aluminum and it would last forever.