Here is the saddle slotting jig I designed a few years ago that has treated me extremely well. It is pretty much a beefed up version of the jig available at Stew Mac. I used a phenolic material known as Garolite, which I sourced from McMaster-Carr. It is very stiff and has a smooth outer surface that works well with router bases. It also a great material for making other templates.

The guitar above is the same 1954 Gibson J-50 from last week's neck reset. This guitar also required a new bridge, so I decided to rout the saddle slot after the neck was reset so to insure the best location for proper intonation.