2 years ago i used cheap Staples mouse pads,and "Liquid Nails" glue,{with a caulk gun}
from home Depot,wich is next to the local Staples,
it quited down the tinny vibes on my side covers, i used One mousepad on each side cover and one on the top cover.
I had to trim slightly with scissors,for the top cover on my inwin case {tower}
still have it,its my first "modded" case, i have a 120 mm fan bottom front, top rear 😉 run the big fans at 7 volt to help quiet them