Between the cutting and filing quite a bit of foam shavings get generated, so I kept my shop-vac handy and cleaned as I went along. In all I was able to make 11 different tombstones with most of the waste being the cutoff material. Once I had all the forms cut. glued and cleaned up I put on a coat of gesso. I suppose regular primer would work, but I had the gesso handy.
To paint them I screwed a long wood screw through the a dog house outside, stuck them on top and blasted them with the stone spray paint.