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.
Membership Chairman-Guild of Archaic Guitarbuilders
Sergeant at Arms-IGPA