I bought some book nook files to use with my S1, but they came with no instructions. So I didn't know how to keep the different layers straight while the glue dried. I just came up with this simple piece to keep the layers straight. It's working really well. The snips are in the picture to help make sure the layers stay down as the glue dries. Please note that this is designed for 3mm Basswood Plywood. If you adjust the size of the file, or use a different thickness of wood, you will have to adjust the size of spaces.