I guess it depends on what you are trying to do. A hot rod goes into a long straight slot, which is best routed on a router table with a fence. A vintage style rod works on a curve routed into the neck itself from the bottom. It is routed, and 2 holes are drilled into the curve from the peghead and from the heel into the slot. The rod is installed and a skunk stripe is put in as a filler strip. You could do that as a rectangular piece in a jig probably more easily than cutting it out. Check out some of the neck building threads by using the search function.
The Finger Lakes Institute for Incomplete Projects
Guild of Archaic Guitarmakers