Created by a team of scientists at North Carolina State University, the material starts out as a solution consisting of copper microparticles suspended in water. Microparticles of another metal, known as eutectic gallium indium alloy (EGaIn) are then added, as is hydrochloric acid.

The latter sets the pH of the water to 1.0, removing oxides from the EGaln and thus temporarily turning it to a liquid-metal state. This causes the EGaln particles (now globules) to cling to the firmer copper particles, forming a network of copper particles connected by EGaln bridges. Methylcellulose is also added, to bulk up the mixture.

The resulting viscous gel can be extruded from the nozzle of an ordinary 3D printer at room temperature, building an item up one layer at a time. When the finished object is left to dry – at that same temperature – the water and hydrochloric acid evaporate. The end result is a rigid, highly electrically conductive three-dimensional object which is up to 97.5% metal (the rest being methylcellulose).