3D function made from flat parts
I've been looking for a good example of this kind of construction for a while now. The idea behind this is that you can assemble a series of thin pieces together to make a continuous, arbitrarily complex curvy surface. Of course, your accuracy will be limited by the thickness of the pieces.
This is a 3D surface function made from a series of thin pieces. It looks like cardboard. The pieces were laser cut.
I've also read about prototype rocket bells being created using a similar technique.