Kuen's Surface, Aqua Eco Canvas

On a surface in Euclidean three-space, straightest paths, those of locally-shortest length, are called "geodesics." Kuen's surface has "Gaussian curvature" equal to -1 (away from curves where the surface pinches to a sharp edge). Concretely, for every geodesic triangle on the surface, the sum of the interior angles (in radians) is equal to pi minus the area of the triangle.

Made in the UK from recycled plastic bottles, stretched over a lightweight recycled frame. Packaging is also made from 100% recycled content.