I am trying to create a heating mat or pad. My requirements are 110V/220V, 140/150 degrees F, and the largest would be about 36"x40" and the smallest about 24" x 24". Can be rectangular if needed, cut to a specific shape is nice. I have been looking at things like under floor heating, and carbon fiber. The problem is with carbon fiber is the resistance isn't less than 15/20 AMPs. Carbon fiber cord works but winding a cord up and down and providing consistent heat is next to impossible. Any ideas? TIA!