Customizing a motorcycle is a big deal and an expensive proposition in some ways, but you can make some really great parts that make your bike stand out, including the motorcycle seat. A motorcycle seat is not easy to make, but if you are used to working with metal, it is not very hard either.
Cut your steel to the rough shape you desire. Leave about a 1/2 inch around the edge of the seat. This part will be curled into shape using a steel curler, so leave enough to achieve the length of curl you want. Account for the curl in your initial shape design.
Run the seat edge through the metal curler or pincher using the right bits for the curl shape you desire. Round off the entire edge of the sheet roughly.
Decide how to make your seat pan, with a "bucket" or concave curl to fit your particular bike and rear end. Then turn the seat upside down and lay it on a mallet bag or form. Pound in the bucket or curl shape for the seat using a mallet. Do this until you form the natural concave shape that makes your seat a little more comfortable and keeps you on the bike. It should also match your overall vision for the bike.
Measure out the foam pieces for the total width of the seat, including the curl, then leave and extra 1/2 inch. Cut the foam and apply it to the seat using double sided tape. Make sure it covers the entire seat. Apply the glue liberally and evenly, then apply the foam and let dry. Apply another layer of foam if desired. You can also use neoprene or another soft, water proof material for this step.
Measure your leather or skin for the bike seat. This measurement will be a lot larger than the foam measurement. Cut a rough shape first, from your measurements, then lay the leather or skin on the seat, and line it up to cut a more precise fit.
Rivet the seat leather to the bottom of the seat using a rivet gun. Go ahead and rivet it to the flat area of the seat, or the side curl, if you want the rivets to show through. That is a cool look. Another idea is to drill holes in the seat pan itself, and lace the leather through to attach it to the pan.
Add your seat hardware and attach to the bike.
