Not long ago I explained to my young pupil how to make conductive drawing with pencil or pure graphite. Anyway, my favorite local art shop announced they brought graphite powder on their website. Graphite powder is the most pure form of -wonderfully conducting- graphite, and easily mixable so I run and bought a bottle of powder. On my way I also bought a travel mini-spray and acrylic black paint.

Once at home, I took out the voltimeter and started mixing. first, some graphite powder and water, painted a bit and measured. ¡Bingo! I could get a bit of potential difference. Although, it wasn't very much and the painting wasn't very strong. I added a bit of acrylic paint... it looked very nice, again painted and measured, still working, added a bit of extra graphite for better conducting, ¡Perfect!

The measure seemed pretty nice, for so I tried out putting a led over the painting and using the resistance+5V wire in the other edge of the brushstroke. ¡Bingo! it lights.

Not as strong as if the were directly connected, but this is because the paint itself creates some resistance, as not every component is equally conductive. The better option here is to use a resistance with lower Ohms, such as 100 ohms instead of 220 (which I used). or also design the painting pattern to be a parallel resistance instead of a continuous.

Continuous:

{LED}-[---brushstroke---]-(resistance)-5V 

Parallel:

        _[---brushstroke---] 
       /                    \
{LED}-<                      >--5V
        \_(resistance)------/

Anyway once I got the recipe, I created a bit more to fit in a mini-spray can, and added a Molotow (one of my favorite graffiti brands) mini-ball inside for mixing when shaking (the tiny ball that makes a sound when you shake a paint can). Decorated the spray with a toxic-green lightning and its done, a conductive spray can.