It begins, of course, with an idea in this metallic free form brain of mine. Then I sketch it out on the computer, drawing curves in 3D space, surrounding them with cross sections.  I sweep those cross sections into developable surfaces, which are surfaces that can be rolled out flat.  The 3D software unrolls and flattens the image, and I export those flattened images to CNC cutting software.   The cut sections are cleaned up,  and I apply texture, reassemble the pieces – kind of like a reverse banana peel, with the banana gone.   The image that began in my metal-thinking mind becomes a reality.