After I lost track of the base plate for the router that goes in my router table, I had to make a new one with accurately marked holes for the mounting screws and a centered hole for the bit. I figured out how to do it while flipping through a machinist's catalog: put a 1/4" straight bit into the collet and a cone-pointed setscrew into each of the router's threaded mounting holes. Drill a 1/4" hole in the base and slide the base over the 1/4" bit. Give the base a tap and the setscrews mark the drilling locations. Drill and countersink for the mounting screws. Before mounting the base, enlarge the 1/4" center hole using a holesaw piloted by a 1/4" bit.
Always a good idea to keep good reading material – such as a machinist's catalog – in the restroom. You just never know what you'll learn!