Over the years, I’ve seen (and used) many different kinds of center-finding tools. Whether they were shop-made or manufactured, they all had a tendency to use dowels, steel pins, or some other type of material that would drag along the outside edges of a workpiece. Recently, while shopping for some shower door replacement parts, I was struck with the perfect idea for an improved center-finding tool. At the heart of this design is a pair of inexpensive sliding shower door replacement rollers. The rollers glide smoothly along the edge of a workpiece. After cutting a piece to size for the base, take your time in laying out the hole locations for the screws that secure the rollers, as well as the hole for the handle. The rollers need to be the exact same distance from the center hole in the base. With the parts completed, simply glue the handle in place and attach the rollers with screws, and this tool is ready to put to use.