I've taken to visiting with a chunk of original (smooth on one side only) tempered Masonite Duron, from 8 years ago.

One place had smooth two sides hardboard, but it was the same mushy material that the Borg sells. The yard workers recognized my sample, though, and said "Yeah, that's the stuff we had back maybe 5-6 years ago, before the change in ownership" (of the lumber yard).

Cheers