In a 2D the answer is two, and a 3D space can be tiled in shapes that have no corners at all, called soft cells. These shapes can be made in a few different ways, and some are shown here.

An AI method enables the generation of sharp, high-quality 3D shapes that are closer to the quality of the best 2D image models. Previous approaches typically generated blurry or cartoonish 3D shapes.

Technology Robots These 2D machines can shapeshift into moving 3D robots Mori3's triangular, modular design allows it to fuse with its companions, and could one day make it into space. By Andrew Paul ...

For the first time, researchers combined 2D printing, origami, and chemistry to create a method of rapid 3D object fabrication without creating any waste material. These shapes self-fold in seconds.

So what if you could buy your pasta of choice in a simple, compact 2D form and then watch it take on the desired final 3D shape as it cooks, thereby doubling the fun factor?

Researchers have developed a technique that programs 2D materials to transform into complex 3D shapes.