Probably the simplest, cheapest solution is to get a bunch of 3 1/4 x 4 1/4 non-slotted film holders and cut down 4x5 film. One of the nice things about the size is the cuts required are very simple- it's 3/4" off both the long and wide axes. The 3x4 non-slotted holders go silly cheap because almost nobody wants them. The slotted ones (they have a lengthwise slot down the skinny edge of the holder, and a cross-wise slot near the rib lock) go for a lot more money because they're relatively rare and they fit the RB Graflex cameras, which are in much higher demand than the 3x4 Graphics.