We bought 10 rolls of this neoprene, good quality and very low price, I then finished them to 3/16'' thick with a disc sandblaster, it does a perfect job, this sandblaster is an incredible tool!
https://www.amazon.ca/gp/product/B005FNGX6W/ref=ox_sc_act_title_11?smid=A3DWYIK6Y9EEQB&psc=1