Conductive Paints

There are a whole variety of conductive paints available, mostly over the internet. Metallic markers and paints that you can get from craft stores are typically NOT conductive. Conductive paints are not cheap, but they are affordable and can be used in many of the processes described in the recipes on this website.

Copper paint from LessMF:

Make our own conductive paints, glues

>> http://smackaay.com/2009/01/13/making-a-conductive-adhesive/
>> http://www.instructables.com/id/Conductive-Glue-And-Conductive-Thread-Make-an-LED/step1/Make-Conductive-Glue-Conductive-Paint-and-Conduc/
>> http://www.talkbass.com/forum/f38/diy-conductive-paint-cavity-shielding-589012/
>> http://www.ehow.com/how_5031497_make-conductive-ink.html

Silver Paints

Tend to be very highly conductive. I prefer water based because they tend to dry/cure at room temperature and are easy to mix with acrylic bases and thin with water. Solvent based versions often have to be dry/cured at high temperatures for long periods of time and are messy to work with.

Conductive Pens

Silver paint is contained in conductive pens that are sold for fixing electrical connections on circuits. I have had little luck getting these pens to work well and dispense their conductive ink nice and smoothly. But you can easily cut them open and extract the silver paint to be used in other ways.
Google “conductive pen” and you should find lots of results.