I've made the seat base from a mixture of neoprene mouse mats and heavy foam. The mouse mats make a very heavy bottom layer, much heavier than any foam I've seen. This was covered with a layer of thick foam and covered with leather. I pulled the leather tight and riveted it in place. It worked out pretty good, without any wrinkles.


 Here it is on the bike. There's going to be a small passinger seat behind the main one but I've run out of foam and I want to press on and get this finished so I'll have to come back to that.