I made mine from a nylon bathroom divider that my local YMCA was throwing out when they remodeled the men's room. They were about 1.25 in thick so I cut 12"x 12" for the jacks and 12"x 24" to go under the tires. Still use them 15 years later. Also made some for home use from 2 layers of 3/4 in oak pallet wood where the second layer was 90 Degrees to the first. The pad is much stronger when the fibers of the wood are 0-90 to each other and won't crack. Screwed together and painted to keep them from rotting too quickly.