The artist purchases a brush, a small canvas, and oil from the art store. He keeps the receipt. He soaks the receipt in salt water, bakes it dry, soaks it in the oil, and places it in the cup of oil as a wick.
He holds a spoon over the cup and burns the wick. The smoke collects in the bowl of the spoon, making lamp-black.
The artist mixes the lamp-black with water to make ink. He loads his brush with the ink and uses it to paint on the canvas, making more lamp-black as needed by burning down the wicks.
On the canvas, he paints a portrait of a gift certificate. The gift certificate is for the store he bought his supplies from. The value of the gift certificate is the cost on the original receipt.
The gift certificate is sold for face value. All proceeds are used to sustain the cycle.