The only drag with this hobby is the sound the tumbler makes for months on end. Its not really a problem for me, as the tumbler is in the shed... but I feel bad for the neighbors. There are tons of articles on sound dampening techniques and Ive tried several, including a plywood box covered with carpet samples. I like the idea of using styrofoam insulation because it easy to work with, has minimal resonance across all audio frequencies, and its non-flamible.

 

Very rough cuts for the proof of concept. Obviously heat will be an issue as Styrofoam's sole reason of existance is to insulate - so active airflow is a must... unless its winter.
An old surplus muffin fan should do the trick. Since I cut the hole in the bottom of the box I chose to orient the fan to suck the ambient air in and let the rising hot air
vent out of small gaps in the top lid.

All fit together and ready for a trial run.

Works great. One of theses days I'll do a sound meter check and report back, stay tuned!