This has to be one of the cheapest and easiest ways to create gears for medium-sized weekend projects. In a pinch, cut some MDF about the same size as the gear you want to make and then glue a piece of automotive timing belt around the circumference. The resulting gears end up matching well with other similar gears and you get the added bonus of being able to use a timing belt. How cool is that? [via Dug North]