PMed you on the launch.
F360 is very cool, very powerful, but it is a time sink. I ran AutoCAD a million years ago, and I have experience with Maya and Lightwave and Blender...and some tool in F360 is always just enough like a tool in one or another of those things to trick me into believing that the learning curve will be short and shallow, Invariably the implementation is different enough from the similarly named tools in all of those things that I hear myself yelling at the computer a lot.
I spend way too much time playing with designs in F360, and not nearly enough time cutting. And it is the cutting that is killing me on wasted time and materials.
The first iteration of the centering rings, I used F360's "trace tool", which ran the bit around the outside of the outer circumference and around the inside of the inner circumference. The offset is half the cutter diameter, so the rings were 1/16" too wide to fit in the body tube and 1/16" too narrow to accept the motor mount tube. I could have filed them down, I should have filed them down, but instead I burned a couple hours playing around trying to figure out the failure mode.
I made the same error when cutting the Garolite inserts. I cut four pieces at once, but I didn't think to check the direction the tool was running. Two of the pieces were perfect, two were undersized by 1/16" in every dimension. This was especially frustrating, since the fiberglass is so nasty to cut.
I am sure that this detail is covered in some tutorial, some FAQ, some reply to some users' forum... but I didn't even think to look until the parts came off the board and did not fit.