Look for a retailer for textiles/fabric that is selling neoprene.
I use a 3mm neoprene mat one side with fabric, the other side pure neoprene.
This is working great as a playmat/dicemat, feels superb and is quite cheap (I in Germany bought a sheet of 55cm x 130 cm for 30€ including shipping)
Where did you get the neoprene? Couldn't find a local store selling it, so now I'm looking for some online store... Thanks.