I wanted to try foam as a new material for me, and I get 2 kinds of foam from art material store.
Two sided parts should be made from flat stock, the purple one is too soft that the right side can not work at all.
The yellow one is much tougher than the purple one, which can be fixed on like a wood block.
I made a wrong setting at first, it should be a flat stock instead of a round one.
Get settings done in a flat stock.
Reset the X and Z axis to 0 points.
Start milling. ( This yellow foam works actually better than I imagined, dusty but not that loudly.)
The final piece is toooo small and not that accurate…