large pan format contact frames are great, but not easy to find, and take some time to make. I've made three. one @ 8x36", one @12x73", and a 18x115" frame. a lot of work. For silver gelatin negs a piece of glass is easier, though David is right you have to watch out that the neg is held tight to the paper. I've found that the felt is enough for the smaller negs, like wade has.It can help to weigh down the glass. I do this with larger negs. Also instead of felt, there is a approx 1/4" foam backed felt available from most fabric stores. A big piece of 1/4" glass on top of this tends to keep the neg in contact to the paper, assuming a pretty flat base I've gotten good results with this up to about 72" negs. weights at the edges of the glass work well for longer negs