Getting 'Round to Making Dowels
To make your own dowels, start by ripping a length of stock with a cross-section that matches the desired diameter. For example, rip a 3⁄8 "-square length for a 3⁄8 " dowel. Chuck a round-over bit matching the radius of the desired dowel (3⁄16 " in this example) into your table-mounted router, and position the fence flush with the bit's pilot bearing.
Make start and stop marks on the fence 11⁄4 " from the bit's center. By routing only between these marks, you'll keep the ends of the blank square to guide the cuts. Place the end of your blank on the start mark at the left of the bit, with the other end angled away, clearing the bit.
Pivot the blank into the running bit and move it to the left, as shown, until the blank's trailing end meets the stop mark to the right of the bit. Repeat on the remaining three sides of the blank. Cut off the square ends.