I was wondering if anyone has any recommendations for materials for machining very fine details for a model (cutting with 0.01" and 0.03" bits). The larger pieces and majority of the model are already made from 15 lb Duna Corafoam, however, its not quite solid enough for the very detailed parts.

I did try making the details using a test sheet of ABS, PVC, and Polycarbonate plastics but in each case the small parts flexed and didn't machine cleanly.

I was looking at maybe general plastic's FR-4600 series microcell foams, has anyone tried these and how do they compare to the duna corafoam?

Thanks in advance!