I'm continually experimenting with advanced techniques for mass finishing batches of parts built with Fused Deposition Modeling (FDM) Technology, and I plan to keep updating you as I make discoveries.
I found it's possible to leave support on parts that have small interior pins or clips to protect them during mass finishing, as long as you're working with breakaway support. (Soluble support is not strong enough to survive mass finishing.) This is not always necessary, but if you start using mass finishing on your specific geometries, you'll get a feel for which parts will benefit.
For parts that have a male and female halves, I recommend assembling them before finishing, if possible, to keep corners sharp and protect interior parts.
Check out the photos to see how this works. The hair dryer has some small spring guides at the top of the handle, so I left the support intact. I also snapped the two halves together for protection.
The white PC meter parts have very thin side walls that joined the two halves. Here again only outside support was removed to protect the thin walls.
Don't forget that build orientation can play a big part in feature strength. Whenever possible, the tool path should run from the body of the part, through into the small features to give them more strength.
For large parts like a toaster or printer housing, I recommend adding a support bridge across large openings. Make it easily removable and consider the cosmetics of the part and easy touch-up. You can see an example in the dark gray strip across the opening of this part. Consider incorporating this into the FDM build and removing it after mass finishing.