Researchers have cracked the challenge of printing glass through a nozzle. A team of MIT researchers have opened up a new frontier in 3-D printing which is the ability to print optically transparent glass objects. They demonstrated the first-ever machine that can print molten glass through a nozzle and make transparent glass objects layer by layer according to digital instructions. The 3-D printer G3DP produces optically transparent glass with the push of a button and contains a "kiln cart...