Mine are by size and shape. I use the clear plastic shoe box size containers. They are cut into 1 1/2", 2 1/2", 4 1/2", and 6" squares --- apple cores, tumblers, triangles, and 3 1/2" X 6 1/2" rectangles, 2 1/2" strips, strings, selvedges and the last one is for bits and oddly shaped pieces for crazy quilt blocks. Right now I also have containers for multiples of 2 1/2" squares (2 each for a four-patch and 5 each for a nine-patch). I'm a little OCD but when you want to something to sew, without a lot of thought, the pieces are ready to go!!!