The weathered texture of these steel pendants is strangely touchable. Some are available with a gold finish as well as bronze, others have free-moving parts that highlight their topology. All are math, art or both.
Sale: I'm moving most of these designs to Shapeways, where you can get them in many more materials and finishes, from $6 plastic to $3000 platinum. So I'm offering my remaining stock of those steel models at $25 apiece.
Exceptions: the first two designs have interlocking parts that can't be printed in steel at Shapeways, and those will remain here at $30. And the little Klein bottle, which is a whole different technology: those are $55 now, but they'll list for $140 after my existing stock is gone.