From the Manufacturer:
Paint with color wax pucks-dries in seconds, less expensive than oil paints and achieve oil painting effects! simply Dip the tip of the Cray-pen into the wax Puck and apply to your surface for endless creativity.
The Cray-Pen is a wallet-friendly alternative to oil paints and encaustics.
Just heat up the tool, dip the hot metal tip in wax, and gently touch the tip to your painting surface — it works with most plastic, wood, canvas, glass, metal, and paper. No solvents needed.