Having burned down once I'm not so quick to use wood for outside structures. Rodents are a problem too. Rubbermaid type tubs solve the rodent issue but they are not sunlight resistant and Are flammable. I haven't done sheet metal since High School 50 years ago but the local plumbing supply has pallets of sheet metal and I got to thinking. I already had the simple 3 foot Harbor Freight Metal Brake from a job making a belt guard and the HF electric pistol shear when it was on sale. Last week I bought the $170 HF Spot welder, 240 volt model as it is 2.5 KW and welds 24 gauge in 1 second. About $400 of equipment plus square, tape measure, scribe and wiring a 240 outlet.
The cabinets are 25x36x36 inches excluding the 2x2 legs. Cost about $50 each including tax, no extra hardware, less than 2 3'x10' sheets of 24 gauge galvanized steel each. The front cover slides up under the top lip then back down to lock the bottom edge. The seams are on the outside in tribute to the original Mini Cooper. LOL Thinking about paint now. Maybe Camo as most of the bins are work related and it would be nice if they could disappear when not needed.