Building a seat pan requires a little knowledge of metal shaping, along with the right tools: metal hammer, metal cutter and shapers, and a mallet bag. The project begins by choosing the right design, and then making sure it fits on your bike. Have the bracings, bolts and attachment pieces ready to fit to your bike during the design phase, so you can be certain you can attach the new seat pan to the motorcycle.
Trace your design on a sheet of paper and then cut out the shape when you get it right.
Trace the shape onto a piece of 12 guage steel or sheet metal using a marker. Leave an extra 1/2 inch around the shape for the "curl."
Trim your seat until the shape is just right.
Run the edges through a metal curler to bend the edges at a curling 90-degree angle all the way around the seat. Be careful when working with the curler and use bits that will give you the shape you want the seat to have.
Spot grind any rough edges around the curl of the seat.
Flip the seat over and lay it on a mallet bag.
Pound out the centre of the seat to get that "bucket" shape for added comfort and functionality.
Smooth out the hammer marks by running the seat through a metal roller, or by rolling it by hand. A metal roller will make this part much easier, so do what you have to do to use one.
Polish the seat using a grinder and buffer until it is smooth.
Make your seat pan match your bike shape and theme if possible. When in doubt, make it smaller, so it doesn't look awkward or stick out and become too noticeable.
Always take care to safely and securely attach a seat pan to the bike, you don't want it coming off!