This question is only tangentially related to woodworking, but may eventually be useful to other woodworkers.
Here's a photo of the guts of my Hitachi RP-30SA 7 1/2 gallon wet/dry shop vac. I've probably had it for 20+ years, and it's been a reliable and not too loud performer all that time.
As you can see, the foam packing is falling apart. Some of these piece are still available as replacement parts, so I'll go ahead and order those, but others aren't, leading me to wonder:
What kind of foam is used in applications like this? I'll need to cut the parts that I can't buy from a sheet of foam, and I'm not sure what to buy.
I believe the job of the foam here is mostly to provide sound proofing, not to act as a filter.