What seems cool about this to me is that they seem to have done it with a plain old FDM printer and copper impregnated PLA. The devices are fairly large (mm scale) so presumably anyone with a $200 ender and the correct filament could print these.

I am able to find copper PLA for sale too, although I'm not positive it is what was used in the experiment, and it's kind of pricey (~ $100/kg).