Gary,
My BRC-250 uses a thick matt black paint. It has a high filler content and has a gritty feel. I suspect it's an epoxy type paint designed for low IR reflectance.
There is a military spec on such paints.
http://www.dstan.mod.uk/data/80/216/00000100.pdf
BTW if you use stick on paper, felt etc, these materials can act as thermal insulators and increase cool down times. They may still reflect IR which could be a problem if you are imaging with a CCD or DSLR without IR filtering.
Regards
Steven
http://users.westconnect.com.au/~sjastro/small