"Are there any sources anyone knows of, for neoprene sheets and tools to cut washers or do they come precut in differenct sizes."
Yes, you can even make gaskets for the driver from about 1/4" thick sheets of soft damped material, such as neoprene. You can get bars, blocks and sheets of various rubber materials(including neoprene) in a variety of densities from:
http://www.mcmaster.com/
For gaskets, about a durometer of 15-20, Shore A is good. For the screw washers, use about a minimum of 40 shore A softness, or the material will keep displacing as you tighten the screw. Do not use a higher durometer, or tighten the screw very much, or the isolation will not be as effective. Use a metal washer between the screw head and rubber. You can also buy small neoprene washers from a hardware store. They come with little metal discs attached, that can be removed. You will need to use 2-3 of them on each screw. I don't remember the exact name of the part, I just look for them and buy them by sight. But, they do specify 'neoprene' on the package. They are about a durometer of 60 or so, a little high, but 3 units per screw is pretty effective. If you choose to cut your washers from sheets, it will be quite a pia. You will need to use leather belt punch to remove the hole for the screw(if you want a clean hole), and cut the OD with an exacto knife.
If you really want to spend the time to do all this, be sure to cut the driver hole deep enough to flush mount the driver, and have the two thick layers of damping, and a ring to seperate them. My last try, I used 2 thick layers of closed vinyl foam..one on the driver hole on cab, and other on the opposite side of seperation ring, and the secondary damping material between driver frame and the other side of seperation ring. But the end result is very effective, with FAR less mechanical vibration transmission to the cabinet. I did not measure with an accelerometer, but in subjective tests, vibration of cabinet, especially the front baffle...was reduced signifanctly. This was on a 1.25" thick front baffle. I do plan to measure the results soon, for a more objective(and accurate) perspective.
-Chris