I have been making contact prints for years just using a sheet of 1/4 inch glass bought from glass shot. Negatives up to 8x10. It is the thick stuff used to make coffee table tops. No need for frosted. The weight of the glass holds everything in place fine, no frame needed. No Newton's rings either. My piece is 10x12 so I have an inch all the way around for finger prints. Have them grind the edges so it is not sharp.