While reading hackaday, I saw that someone copper plated a 3d print using a solution of acetone and graphite powder. After quickly creating some copper acetate from a equal amount of 3% hydrogen peroxide and 6% vinegar and some copper scrubbers, I had an idea besides the obvious copper plating of 3d scans of my children.
I have yet to try this, but it seems possible. I will test this tonight and report back later. So, design and print an object, lets give it some LED eyes for fun. I guess I could just run a couple wires through a predefined area and then connect the led in each eye. Or, I could paint on some graphite and then copper plate the traces!!!! This may not work, but the idea is sound. if the resistance is low enough and the traces are OK, I should be able to either use conductive glue or actual solder to attach the pieces. Since you would want breaks along the pathway for components, you would either have to attach the cathode to each broken section, or you could paint the mixture on to the entire pathway and scrape off the area that needs the break for the component. I will try the latter first.