This is kind of a how to if you want to make a cafe style seat.
I happen to make this out of 18 gage steel.
1. Make a template for your pan. This kind of depends on your size & how you want to sit on your bike.
2. Decide material: Thickness, steel/aluminum, etc
3. Measure twice
4. fit the pan to your bike. I used the stock brackets, rubber supports, and lock.
5. decide what kind of shape you want on the back