Graphene 3D Lab has been working tirelessly on a Graphene/PLA composite material which can be used within most FDM/FFF 3D printers. The material is highly conductive, can be used for Rf shielding, and capacitive sensors. The new filament was launched under a new brand named BlackMagic3D. Priced at $65 per 200 grams, it certainly isn't cheap, but if the filament has the properties that the company claims, it may just be worth it. The new filament will work on most printers which have a heated bed (50 degrees C), and can extrude at temperatures around 170 degree C. More details on this new graphene filament, and the new BlackMagic3D brand can be found here: http://3dprint.com/51502/black-magic-3d-graphene

Below is an example of a functioning print created with the conductive filament used as circuits: