Has anyone any bright ideas how to make shallow, blind holes in closed cell foam? It is Plastazote foam so quite dense and stiff.
I want to make 12mm or 15mm diameter depressions about 3mm deep (the foam is 10mm thick).
I was wondering if using a plunge router or a pillar drill with a forstner bit might work. I have a router and a small, quite high speed, pillar drill. I don't at present have any forstner bits.
So I will probably try the router but opinions on the forstner bit instead would be welcome.