Hello all noisy tumbler operators. I have an idea that those in
the shop driving you crazy were being run on a hard surface, so
putting a box over it isn't the answer. Nor is a sound-proof room
practical for most. Try buying a thick as possible carpet remnant
for the floor, covered with a heavy as possible rubber mat of the
non-flexible variety. Then your tumbler will purrrrrr.
Comparatively, that is. Works for me.