Chassis damping material

What are some of the cost effective material for audio chassis damping ?

I am aware Audioquest have those sorbothane sheets that have an adhensive on one side for sticking onto the internal chassis.

Herbie Audio Labs also have some silicone-based viscoelastic sheet for similar applications.

What are some good ones you have tried ? Please share your experience.

look at some automotive audio sound stores,,,,they sell products that in many ways r cheaper and better suited then many of the run of the mill over priced audiophile stuff...the best to u
Try looking at EAR ISODAMP SD, which are self adhesive sheets and are available at Michael Percy Audio. In particular, look at the SD40AL which has a layer of aluminum for something called "constrained layer damping", which in the world of vibration control sheets is a very good thing. If you are on the cheap and you need lots of vibration control material, consider Dynamat sheets that are are typically used for automotive sheet-metal dampening. Here again, look for the aluminum-clad sheets used for car firewalls. If you should feel that both these forms of dampening sheets offer you a little too much of 'deadening' or 'rubbery' effect on the sound (possible IME, but unlikely) then I would consider what a Japanese firm has come up with called "fo.Q High Damping Material". Details about the exact scientific principle upon which they work are a little sketchy and I haven't actually used them myself...yet, anyway, but people who've tried them have raved over them. 2 different types, 1 for enclosures and 1 actually for wires and cables. Any of these (the fo.Q, the Dynamat or the EAR) will be useful for most chassis apps, particularly if they have not already been treated with other forms of vibration control (like brass footers) which might be working on a completely different principle (draining, rather than isolation) and actually end up at cross purposes (masking the sound a bit rather than revealing it). Of course, if you're going to treat a given component by either by isolation, by draining to a sink or by vibration suppression with these sheets, then I would suggest you stick exclusively with that strategy for that component and don't mix-n-match. All your gear will likely benefit, but if you have a CDP or tansport, it may benefit the most if you experiment with the tray and as many parts of the mechanism you have access to and that will still move without impeding their operation. Better bass by far and usually better highs and soundstaging.
Cork, cork, and again,...cork! Why don't I have the privilege of submitting a one word response?
Because cork lacks sufficient mass. ;-)
Moongel, available at stores where musicians buy drums. Six dollars for four pads. They work.