Mikey77 made a small 3d printable electronic circuit and created a detailed how-to guide on Instructables. It is made on a regular FFF DIY 3d printer (Replicator 2) shaped like network of grooves and holes in a printed board filled with DIY conductive glue which closes the electric circuit.
Video of a working printed circuit:
Detailed building instructions, .stl circuit files and more photos:
DIY conductive glue which closes the electric circuit:
Here is an updated and more detailed guide with more components and sensors: