I recently purchased some conductive ink from these guys, https://sites.google.com/site/thinkinkfactory123
far better than Bare conductive as Bare is a thick sludge which did not work very well when I managed to get it out of the pen, the Think Ink product is really nice to work with as it is like a paint, looks great as it is a silvery metallic colour and I actually recorded 2 ohms per square which is definitely not possible with Bare's gunk in a pen!
Great, now draw out the pathways for a circuit and see if it works. Start with a single LED and see how far it can go.
I am working on a project about ink printing. The ink I used made by ANP