I saw some interesting projects using polycarbonate as material to create a mold. With this and a fantastic ebook by Paul Jackson, Folding Techniques for Designers, I created and cast an interesting geometry.

I first etched fold lines into the polycarbonate using a laser cutter and folded in the appropriate direction along each of the lines.  The structure was very interesting to put together and manipulate. It could be folded into many different geometries and could achieve double curvature.

Once formed, the mold was sealed and I used 'marble cast' to create the positive final piece.