TT mats

My experience is limited to a number of 401s with aluminum platters.
1. Boston Mat 2: energy suck, "cleaned" up the sound by removing microdetails including spatial cues, air and life.
2. Std. rubber mat: adds lushness and musicality. Smears mids and highs. Adds bass bloom.
3. 10" vinyl record: removes smearing and coloration (possibly due to the store and release of damping). Increase in detail, speed, air, transparency. Improved bass definition. Possibility of a little added brightness. This is what I use.
4. Cork, paper, felt, leather DIY mats: Meh. Not worth the effort.

@bdp24 Where are you getting Isodamp pricing? What you’ve posted is a nonsensical price.

Isodamp C-1002 Series 0.125" thick, 54" by linear foot is $68. That’s a lot of material. Can be ordered from the authorized distributor direct: https://www.rathbun.com/c-40-damping-isolation-materials.aspx

Michael Percy sells SD Series (what SME uses) 0.125" thick, 12" by 27" for $60. http://www.percyaudio.com/Catalog.pdf

Both sources have other thicknesses and sizes.

@bdp24 I would just place a record on top, trace it, then use sharp scissors.

The SD series from Percy are all adhesive backed. The strength of that adhesive is practically permanent. If you decide to try it, I recommend doing so without removing the protective film. 

Thanks invictus005, but the Isodamp is not for my tables, all which have platters made either entirely of Delrin (Townshend Audio Rock), or aluminum with a top layer of Delrin (VPI). I have looked at the Isodamp for constrained layer applications, but didn't know it was available in black, as the SD-125 is. A lot of it is available in blue only.