Hyperboloid Burr is a six-piece burr six-piece burr, made of six identical hyperboloid pieces. It was designed with the help of Naoaki Takashima. The wooden version was made as a limited (sold-out) edition for Naoaki Takashima by the Kanagawa Toy Company in Odawara. While working on the wooden pieces, the manager of Kanagawa Toy found an unexpected 7-piece solution.
The Shapeways version has the same shape as the wooden, and it has seven pieces, so you can try both challenges.