You might think that 3D printing is a mature technology, the way guns and pizzas and pieces of jet engines are popping out these days, but you haven't seen it all: a company called Mataerial has built a contraption that can print gravity-defying strands of material right onto a wall.

 

Where existing 3D printers deposit tiny beads of melted plastic (FDM), solidify resin with ultraviolet light (stereolithography), or fuse powered material with laser beams (SLS) to form a part, these technologies typically require a flat tray where the work is done. Not Metaerial: because the robot arm deposits a mix of thermoset polymers (the company's not saying which ones) that harden at the exact same time they're pushed out the tip of the extruder, it can appear to generate threads right out of thin air. The company claims its printer can even print an object in multiple colors simultaneously, by injecting colored dye mid-strand.