just like the factory ,jute, you can buy it at carpet stores. But i found they want you to buy a large piece or nothing.

I bought a 12x12 section of 1/4 inch at a yard sale.I can cut it in half and sell you some. For the heat you can buy the reflective blanket material , like the one used on the doghouse/engine cover in a van. that stuff isnt all that expensive.Im only going to use it right where the mufflers are under the rear seat.