if what is wanted is a metal frame of about 8 1/2 x 11 with a plate glass hinged at the top-

goto adorma or b&h website

have seen them in both stores

30 yrs ago i had one made by paterson and it was a solid well made example of over engineered overkill-wish i still had it

take a piece of glass or plexi or acrylic and duct tape it on the short dimension to a peice of cardboard or pressboard or plywood and you have the same thing for about $2-$5

if proofing just put the negs still in pages(you do store your negs in clear plastic pages in a looseleaf binder don't you?) in the sandwich and expose

if contacting a neg for a finshed print add some bulldog clips or the plastic ones used to close chip bags around the edges so that htere is enuf presure to maintain good contact

vaya con dios