Up until now I have used (in chronological order) a popsicle stick/scalpel jig, a Dremel/home made compass jig, a drill press cutter and a laminate trimmer/multiple centre hole base plate jig to cut the rosettes and sound holes on my guitars. Each new jig has been better than the previous one, but they all have their own set of problems too.
Last week end I made this jig, based on pictures on Sylvan Wells excellent site, and I think finally I have the ultimate rosette jig. Sylvan credits Tony Karol as the inspiration for his jig, and I have seen several other similar ones posted here, so I here's a big thank you to all you guys, you know who you are!
Disclaimer: I have not had a chance to test it yet, my new 3,3 KW 230V/110V site transformer (thanks for that tip Colin S!) has not arrived yet so I the new PC trimmer has not been used yet either. However, the jigs feels very solid, the adjustments are smooth yet firm, so I'm sure it will work beautifully.
The materials I used was just stuff I had on hand: 15 mm acrylic, 6M threaded rod and assorted parts from a discarded router fence (I didn't have a Telecaster knob like Sylvan, so I super glued a chunk of ebony on the threaded rod and turned it in the drill press!).
You pretty much see how the thing works form the snapshots, so here you go:
Top view:
Side:
Bottom:
