Josh Smith ran across a excellent ABS post processing machine at Walmart, in the kitchen section. It is the Presto Part Finisher, aka the Presto Kitchen Kettle Multi-Cooker Steamer.
He outlined his results in a post to Soliforum. In short, pour a small amount of acetone in the bottom of the pot. Place the prints in the basket, and turn the heat on just until the light comes on, maybe a little more. The acetone vapor will begin to fill the pot until it begins to condense on the lid. At that point, turn the heat off and pull the basket out of the pot, having left the prints in the vapor for about 30 seconds. They can be touched after a few minutes, but will be a bit soft for 40-60 minutes. I put screws into the bottom of the basket so it would sit higher above the acetone, and covered the bottom with Kapton tape to make a smooth surface.
Like my needlessly complicated DIY version, use this outside. Also wear a respirator, or you are likely to have a sore throat for the rest of the day. I put together a short video of me making a knob for my printer door, using Crysta-Line Topaz ABS from 3Dprintergear and http://www.thingiverse.com/thing:30335, using the Presto at the end.