People so rarely use light string accompaniment as the soundtracks for their 3D printing projects these days, but I think this video deserves it. It depicts a new, syringe-based metal printing system made by researchers at NC State. It uses gallium and indium which oxidizes in air, thereby sealing the droplets together. While you won’t be building any 3D guns with this process - it’s far too slow and the dots are microscopic - you can create self-healing wires and stretchable circuits.