I would really be interested in seeing some samples exposures from your Dandy. If your camera is the 4x5 version, and you are impelled to use a standard 4x5 film holder in your camera, I found a simple non-destructive modification that worked with mine. Sticky-backed Velcro comes in narrow lengths. There are two parts to Velcro, the fuzzy side and the side that has the microhooks. Using the fuzzy side only, I lined the inside of the camera where the film holder would meet the wood. A modern film holder is somewhat narrow as compared to the original plate holders, and the fuzzy side of the velcro strip works great to fill the gaps as a very durable light seal. I also applied two layers in the bottom of the camera to fill that void, and then I applied a narrow strip on both sides of the top of the holder itself, acting as a light seal where the holder meets the top of the camera.