Convolution is a seven piece serially interlocking puzzle designed by Stewart Coffin, probably the greatest ever puzzle designer. Stewart has generously placed his designs in the public domain, so I am delighted to present my own interpretation of this lovely puzzle. I made my first copy out of wood over 25 years ago and it is still one I go back to periodically. One of the moves includes a rotation and every move locks the next piece into the previous one. The pieces of the puzzle are composed of juxtaposed hollow cubelets using a new design. This gives the whole puzzle a lightness and slight flexibility. It also means that the pieces fit snugly together. The whole puzzle is 4 x 4 x 4 cm in size and relatively inexpensive for a printed puzzle of this size.