I've done several of mine, the hardest (& most expensive part) is finding firm enough foam. My first project was a passenger pillion for my wife. I bought some "firm" foam online, shaped it with an electric kitchen knife & sanding disc on my electric drill. Turned out nice but after sitting on it a few minutes it basically collapsed. I finally bought some foam from Sargent Cycle in Florida (their closed cell "Atomic" foam. Great stuff but VERY expensive. Also, if you need to glue layers of foam together, use some contact cement (like you glue laminate to countertops). Good luck & if you find a cheap source of GOOD FIRM foam, please post.