They're scary! No room for mistakes. I cut the ring to inset for my tenor tonight. I used Sheoak since I'd used it for the tail graft already and I think it'll look great against the western red cedar top.
It took 2 tries after I miscalculated on the first one... maybe I can use it for a soprano down the road.
I still need to cut the groove in the top to fit it in and the ring is also WAY too thick still. I'll have to sand it down some, maybe before gluing it to the top (I'll use double stick tape to hold it down so it doesn't move and crack).
The top is only about 0.070" so routing halfway through is "interesting". It's hot and sticky in my garage now and the mosqitos are coming out... I'm going to wait until tomorrow so I don't rush it and make a mistake. I'll also cut a groove in a test board first to make sure it's RIGHT before cutting my top.
I'll also cut the soundhole while I'm at it... I suppose I should cut the soundhole reinforcement plate while I'm at it too... so much to remember...