I do mine on the baseboard. Paper, negs , glass. I pull the negs out of the clear files (I got bad results trying to print thru them). I can do a proof sheet like this very quickly. I also do my 35mm like this as it's way faster than loading up my 35mm proof sheet frame. My only advice is to get a piece of glass wider than the baseboard so it hangs over the edges enough that you can grab hold of it and lift it off easy. keeps any fingers prints to the edges and out of the way too.