Electroninks Incorporated is raising funds for Circuit Scribe: Draw Circuits Instantly on Kickstarter! Circuit Scribe is a rollerball pen that writes with conductive silver ink. It makes creating circuits as easy as doodling.
The viscosity of the liquid is the key part. The effect is like a siphon, where the lower down liquid can transmit (via the viscosity) some of it’s energy to pull the upper part over the rim of the beaker.