The max slope you'll see on a long body with a tight back radius (15') is about 7 degrees on the back near the heel, so using a 10-12 degree angle when milling the donut will take care of any clearance issues. 1/4" aluminum is good for the base, and gives you more usable depth when using the shorter SM bit set. With a Bosch Colt, the base mounting screws will be outside the donut if you keep the diameter under 3-1/2"...makes getting the router off the jig easier if you cannot dedicate it to just that jig.

Here's a 12 step procedure for milling a donut.

I use UHMW plastic, which is a little slicker than corian and mills a lot easier, but does not take as fine a polish. An alternative is Delrin, which is slicker than slick, much cleaner cutting, and about four times the cost.

Easy to make on the table saw. I need to do one of these for a jig I'm making, so easy to do a second if you need one.

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