The more you file out the carrier, the less flat the negative will be. Everything is a compromise. For small enlargements that is fine. For big enlargements (11x14 and bigger) you will have some difficulty getting the corners sharp. If you don't intend on showing the filed out edges of the holder, a glass carrier can be a better solution. Also, realize that most cameras don't show all the way to the edge of the negative in the viewfinder, so you will be printing stuff you didn't see when you snapped the shutter, if that is what you want.