ShrinkyCircuits is a novel circuit prototyping technique that enables children to experienced engineers to create durable circuit boards that come in any desired color, shape, and form. This fabrication utilizes a commonly used thermoplastic material, ShrinkyDink, as the circuit substrate. This allows users to freely draw and paint to decorate the substrate, and sketch the circuit with commercially available conductive pens. The results are beautiful, fun, and relatively-durable circuit boards that cannot be achieved by traditional PCB or other circuit sketching methods. As a bonus, the conductive ink wraps around the electronic components as the substrate shrinks, thus forming a solder joint around the through-hole components during the heating (with oven or craft heat gun) process - viola! self-soldering circuits!
Joanne Lo, Eric Paulos, "ShrinkyCircuits: Sketching, Shrinking, and Formgiving for Electronic circuits", ACM UIST, Hawaii, October 2014