Silencing mods I have seen:
- Softer rubber feet and/or desk mat under the keyboard.
- Thicker keycaps: However, to be compatible with silencing clips the switches on the keyboard must be oriented with the LED window down/towards the user and practically all keyboards with backlighting have them the other way around. Thick keycaps in Cherry profile will still hit the silencing clip when you bottom out, reducing key travel with a fraction of a mm.
- Put putty inside all cavities within the keycaps to make them even more heavy and solid.
- Put electrical tape inside on all edges where a PCB or plate is resting, and under stabilisers.
- Fill the cavities inside the keyboard with mats of bitumen. (used for vibration-dampening in automobiles)
The latter three mods can be seen
in this gallery. The text is in Swedish but the pictures are good enough to speak for themselves.
Some keyboards (like the Input.Club K-type) have stabilisers that rattle - which is often because they are not genuine Cherry stabilisers but clones with thinner wire. A change of the stabilisers and some thick lubrication fix them.
Then there are people who use "switch stickers" and/or gold-plated springs, but I don't know if those make much difference.