Carla,
I make my own hip and butt pads using dense foam rubber. I shape the foam using an electric knife (the easiest way to cut foam). I like to make my own pads because then I am in control of the shape and the amount of curve I want. I made several sets before I got the shape and size I wanted, and they look good quite good worn under a firm panty or spanx.
Hugs,
Sally