Maintaining fine details while applying smoothing methods I've been reading and experimenting with Acetone vapour smoothing on some printed ABS parts. My problem is that I need to selectively smoothen the printed parts which vapor smoothing doesn't allow. In particular, the cogs, whose sides I was trying to make smooth ended, up with smooth rounded tips, which was a disappointment.

An example of what I was trying to smoothen is would be something like this: 

So how can I maintain fine details (like the cog tips in the image above) while applying smoothing methods to printed parts?
A technique I've used in the past is to make a acetone slurry of the same filament used to print your object, and carefully paint the details you need to smooth.  You must be careful and only do a very thin coat or you may damage your print. You can add extra coat if needed to make sure the acetone has evaporatored from the previous coat of ABS filaments slurry.