For this figure I decided to transform a surface two times over a single object. Usually I work with a single transformation from one state to another, which can be confusing enough to look at. With two transformations the object needs to be larger, because if they are cramped together it will just look like a mess.
I was working with the center surface, to turn it into a ledge and a ridge, but then I realized that a greater illusion lies in the elevation changes that this generates.
If you start on the right side of the bar you will see the top sticking out, in the middle the bottom is sticking out and to the left it is all flat.