They have machine mats at sport stores like Sports authority, Modells, ****'s. The mats for machines are generally on the thinner side (1/8") and are specific to cut down vibrations. Chances are if you get a mat made for equipment you could cut out your dimensions and store away the rest for the future if you change tanks and want to use it again. For 1/4" thick pieces that puzzle together, you can find those at the sports stores or you can got a 5 and Below, they sell 24"x24" pieces for $3 ea.