X-posted from https://www.reddit.com/r/MushroomGrowers/comments/6v7pa5/i_made_a_pc_muffler/

For those with thin-walled apartments who don't want neighbors wondering why you're running a PC every day.

This is a "muffler" not a "silencer." It reduced the overall noise and removes most of the 'rattling' sound. As further audio camouflage you can run the dish washer and/or play some music in the kitchen to mask the 'steam escaping' sound.

The inner piece is an open cylinder made by cutting off both ends from a larger-sized soup can (the kind you don't need to add water to the soup). The outer piece is a large metal coffee container. The white stuff is regular polyfil, and is filled all around and inside the inner can (leaving room for the rocker) and all the way down the inside of the larger can. Don't pack it tight, but not too loose either; snug is best. The two cross bars are to keep the outer can elevated above the inner can so that steam can escape. Don't use coat hangars for the cross bars, they'll rust.