That's the good bit about a quarter-plate camera -- Polaroid IS quarter-plate. Or you could look for an old 9x12cm camera designed for single metal dark-slides, either baseboard or doppel-klapp. These are usually much smaller than 4x5 inch.
Originally Posted by jasonjoo
It's also possible to to make a body to go on the front of an adapter and stick a front-cell-focusing lens on there. All you need is a simple pyramid. I actually made one out of cardboard, but thin sheet alloy or plywood would be better. Then stick a front-cell-focusing lens (in a shutter) from an old RF folder on it: surprisingly many 105s will cover quarter-plate Polaroid. All you need then is a wire-frame viewfinder.