Adrian -- Just to follow up (and I don't mean to be argumentative, as you obviously know more about this than I do), imagine taking one of the corners in my profile, removing it from the rest of the profile, and turning it into a closed triangle by adding a third side. Now, if I told Cut2d to cut an outside profile around that triangle, it'd have no trouble producing a toolpath that would yield the correct triangle, with its sharp, non-rounded corners. Notice that 2/3 of that hypothetical toolpath (i.e., the portion that includes the two original legs and the corner they define) is precisely the same toolpath that I want for the 12 sharp corners of my inside profile. I think that the only difference between the hypothetical and my actual scenario is that in my case, Cut2d is using its "inside" profile algorithm, while in the hypothetical case it's using its "outside" profile algorithm. It's clear (I think) that I can manually (e.g., in my CAD software) construct an "on" profile that will yield the toolpath I want by offsetting (on the inside) from the original profile by half the cutter diameter and dealing with the corners using the same strategy Cut2d uses to create toolpaths for external corners in outside profiles (there are actually myriad ways to do this, particularly since I don't care what happens to the material inside the profile), but it seems like there should be some way to make Cut2d calculate such a toolpath automatically.
Am I missing something?