Bracken Dawson and James Bruton of So Make It, the Southampton Makerspace, demonstrate the acetone smoothing technique for ABS prints in a recent video. The technique is well-known, but can be tricky and is also potentially dangerous if you're not careful.
Nevertheless, the duo walk you through the acetone process, demonstrating issues such as effect of the variable thickness of the acetone vapor, mounting challenges and more.
In spite of the challenges, the results were very good, as you can see in this image.
One problem encountered by the team was caused by placing the objects on a chunk of wood while in the acetone chamber. The liquifying ABS plastic seeped into the porous wood fiber and basically bonded the object to the wood. Not a good plan. We recommend suspending the objects in the vapor with a coat hanger or wire loop.
While the results can be impressive, there are limitations. Fine details, for example, will be obliterated by acetone smoothing. Also, the process works ONLY on ABS plastic. PLA plastic will surf the corrosive vapors without any trace of change. Finally, we must reiterate the danger of acetone. It's a highly flammable corrosive substance. Any time you place acetone near heat, be exceptionally careful.