The Klein Bottle a surface with only one side, a mathematical joke if you will. Just as it's about to enclose space like a regular bottle, it curves back with a twist and the inner face merges with the outer – and suddenly inside and outside are one, like the side of a Möbius strip.

Because the surface crosses through itself this neat trick can't quite exist in three dimensions, but to the best of my Euclidean ability here is a nice approximation. It's is 3D printed in stainless steel, with some bronze for color and a little patina and polish. It's durable, washable and ergonomic, sized to fit the hand sweetly.

The perfect finishing touch for any math fan's kitchen, and fun to explore for anyone.

Yes, it really opens bottles!