I tried taking a sander to one of my paintings, so the surface went from this:
It reminds me of Fimo clay (but who wants their paintings to look like Fimo clay?).
I wore a respirator while I did this and I did it outside, but of course I was still filling the air with acrylic paint dust, which seems like a bad idea all round. May sand it down more though, if I get a warm day...