I spent a lot of time looking around for howto resources on the web, and the one I kept coming back to was diymotorcycleseat.com. There's a ton of good info there.
THINGS YOU'LL NEED
- a seat to modify.
- a raw gel pad. We bought one of these from Saddlemen
- finishing/smoothing foam. I'd recommend going 1/2" thick on this. I bought 1/4" foam out of concern for adding too much height to the seat for Shagzwife, but I ended up double-layering it once she tried it out. I got mine here (I bought 1 yd of 1/4" x 27", about $10 shipped)
- spray adhesive. I used 3M Super 77, which is easily find-able at Walmart.
- something to cut the foam (and gel, if you choose) with. Knife, Dremel, etc.
- stapler (see below)
- flathead screwdriver or tack puller
- a marker
- angle grinder or drill with a low abrasive sanding disc (I used 120grit)
- respirator/dust mask
- eye protection
A few notes on those...
Whatever you choose to cut the foam with, you'll have two different kinds of foam you're cutting through. Your seat is going to be a more dense foam than your smoothing foam. I've seen more than once place recommend an electric carving knife for doing foam cutting, since it's essentially a low-rent version of a nice foam cutter. That probably won't work too terribly well trying to do smaller, more precise work, so you'll probably want an exacto or something of the like as well if you go that route. Personally, I just used a dremel with a cutting disc. It did everything pretty easily.
As for the stapler, everyone's posts I read on the web said that a regular spring-action hand stapler won't cut it alone and you'll end up having to pound your staples in the rest of the way with a hammer. Some have had luck with heavy duty electric staplers, but the general consensus is to use a pneumatic stapler if at all possible. You'll want 1/2" crown staples, 1/4" or 3/8" deep.
I had a bit of a saga trying to get my hands on a stapler, so I'll tell you this much.... Home Depot rents staplers, but they only have electric ones typically used for flooring, which are far too long. Harbor Freight sells a pneumatic one for $20, but at the time I'm posting this it's on back order (which with them, who knows if they'll ever get them off back order) and I couldn't find one in their stores [link]. I ended up buying a Craftsman from Sears (this one). It's nice, though more money than I was hoping to spend on this project...but hey, I have a stapler whenever I might need it now, right? That said, I now have a stapler that can be rented for the low low price of $beer.
I would seriously recommend not skipping the respirator (I just used a cheapo 3M mask I got at Home Depot for a couple bucks) or eye protection. Seat foam dust is some seriously vile shit and will get EVERYWHERE when you start cutting and sanding your seat. I seriously would not want to be breathing that stuff.