Using Conductive Paint
Conductive paint comes in 5–10-gram syringes.
You might also want to look into conductive epoxy (preferably single-syringe one-part epoxy) and/or conductive tape.
Additional Supplies
Safety glasses
Gloves
Lab sink
Paper towels
Cotton swabs
Surface cleaner
Preparation and Cleanup
Caution: Wear safety glasses and gloves whenever working with wet conductive paint and wash your hands throughroughly afterward. Failure to do so may result in conductive paint or water contaminated with it in your eyes or on your skin.
Do all of the following over a lab sink. Do not wait long between steps to prevent the conductive paint from drying/hardening in the nozzle tip of the syringe.
Preparation
Unscrew the cap from the nozzle of the syringe while holding it upside-down, without putting pressure on its plunger.
Screw the widest possible nozzle tip into the nozzle. Its greater contents take longer to dry/harden and it may be cleaned out using a cotton swab.
As slowly and steadily as possible, press the plunger until conductive paint fills toward the end of the translucent tip.
Clean excess conductive paint from the tip using a paper towel.
Cleanup
Unscrew the nozzle tip while holding the syringe upside-down, without putting pressure on its plunger.
Screw the cap back onto the nozzle of the syringe.
Rinse the tip, clean it out using a cotton swab, and dry it using a paper towel.
Caution: Be extremely careful not to spray up water contaminated with conductive paint, especially toward yourself. Failure to do so may result in conductive paint in your eyes or on your skin.