Bare Conductive's Electric Paint is just like any other water-based paint... except that it's electrically conductive! This means that you can actually paint wires onto things like models, clothes, furniture, walls, almost anything you can think of. Standard acrylic or water-based paints can even be used alongside Electric Paint to act as insulation or to create multi-layer circuitry!
Oh yeah, and now? It comes in a pen! Bare's Electric Paint Pens are a great electronics prototyping tool for makers of all ages. Nontoxic and water-soluble, they can be used without gloves or mask. Once applied the paint dries quickly at room temperature, and can be removed with soap and water.
Note: Electric Paint is not meant for use on skin!
Note: Electric Paint is not waterproof, but depending on what your application is you can paint over it with a waterproof paint or varnish. On the bright side this does make for easy cleanup.