Tech pros have used 3-D printing for everything from prosthetics to toys. It could hit the mass market in coming years thanks to a combination of cheap at-home printers and e-retailers like Amazon. But researchers are still pushing the boundaries of what the technology can do. The Mediated Matter Group at the MIT Media Lab, working alongside the MIT Glass Lab, has unveiled a 3-D printing technique it calls Additive Manufacturing of Optically Transparent Glass. Because molten glass is extremely hot, MIT’s printer relies on a “Kiln Cartridge” that operates at roughly 1900 degrees Fahrenheit; the glass squeezes through a nozzle crafted from alumina-zircon-silica. “The project synthesizes modern technologies, with age-old established glass tools and technologies producing novel glass structures with numerous potential applications,” the group wrote in a posting on Vimeo. The video accompanying the posting is well worth checking out. Could at least some of the glass items in your house (or office) soon be 3-D printed?