Video of Solids of Constant Width

[Jonathan]

My approach would be to turn the pointy bit and then basically part off the lightly curved face first roughing a relief down to maybe 10mm dia and then finishing the face and parting off the final 10mm in one go - if you get the tool shape right it should work ok.

Anywhere near? :-)

I thought it might be that, but there's no mark at all at the center of the lightly curved face.