Their Oillight is quite the statement. The lamp explores the scarcity of natural resources, fluctuating oil prices and consumer demand. There are several different oillights each made on a different day. Because of the differences in oil prices also affect prices for oil derivatives such as the plastics that are used for 3D printing the lamp becomes bigger or smaller on each different day depending on how high the oil price is on the day when it is ordered. 

Each little barrel represents $1 and so the entire lamp which is a cluster of them accurately represents the price of oil on that day. A series of oillights then make up the Oillight work which shows you the fluctuation in oil prices over a given period.