There are Arduino Shields open source hardware project. We modified the normal method with crafting idea to decrease the cost of prototype board and conductive pen. We made PAPERduino "stable" decreasing the cost more... https://thecustomizewindows.com/2015/12/build-own-arduino-board-paperduino-arduino-shields/
Ohaus Pen Meter ST10C-B Conductivity pen meter, measurement range 0.0 – 1999μS/cm
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.