"He who marches out of step hears another drum." ~ Ken Kesey
We have a BBHO brand, model 2345 UV fluorescent tube exposure unit...(Anybody ever heard of this brand/model, I haven't!) Went to a local sheet rubber vendor, and bought a big chunk of closed cell neoprene....I'm in Ohio, so I've never had one on to verify, but the supplier told me that it's wet suit material...If one can ignore the lovely Magenta cloth on top, it works fine. It's been a few years, but I think it was only about 15 dollars for the material.
I think Foam Order was backordered on the size/thickness I wanted so I ended up finding these folks. Also CA based.