This is one I made for doing signage. The rollers are pvc pipe with plugs that have bearings (do a search for "roll end bearings for PVC pipe"). The frame clamps to the end of a table, the paper feeds down between the rollers. The weight of the roll would keep just enough tension on the paper that I could feed out about three feet, anchor it down to the far end of the substrate, then slowly work my way back towards the roller with the nylon sign "squeegie" thing eliminating most bubbles. The two metal uprights are just truss anchors to keep the roll more or less centered. The bearings were the only real expense and I don't think they cost that much.
