I've printed quite a few test-Marvins now in ABS, let's throw one of them in an acetone vapor bath!
The setup: big glass jar, a little bit of acetone, a small 'table' that fits in the jar and a heatbed.
Put the jar with acetone on the heatbed at 100°C and put the ABS piece in the vapor for a couple of minutes.
The result: smooth parts!
Warning: Acetone is very flammable and the fumes are not very healthy!