Not long ago I was part of a discussion about using mechanical things to demonstrate computing concepts (such as building a learning Tic-Tac-Toe game out of matchboxes). This got my head spinning on different ways to use mechanical devices to compute things, whether or not such computation is useful. I figured I had enough Legos lying around the house to make something interesting. I started by thinking of some of the more famous early computers, such as Pascal’s calculator and Babbage’s difference engine.