I am constructing two oil storage tanks for a customer located in New Zeland. The drawings he sent me are metric, so the first thing I had to do is convert them to 1/4 scale. One tank will be 12-3/4 inches in diameter by 14-3/4 inches high. in 1/4 scale that is 51 feet in diameter by 59 feet high. The other tank is 18 inches in diameter by 18 inches high coming out to 72 feet in diameter by 72 feet high. These will be the larges tanks I have ever constructed. I will use .0.20" thick styrene for the shells bottoms and roofs. I am just starting and you can see the two roofs and bottoms in the pictures. The models will go in a display case. The real tanks were constructed under the supervision of the customer at a Shell Oil facility. These tanks are very tall for petroleum storage. In the US, most large petroleum storage tanks are 40 to 56 feet high.