Due to their susceptibility to rust, steel storage units should be avoided. Among metal storage units, rust-free aluminum is usually the most sensible choice in siding. Metal siding is hardly the most visually appealing choice.
Do-It-Yourself Outdoor Storage Buildings vs. Professional Installation - If you'd prefer that most of the work be done for you, then just select a shed from your local home improvement store and ask that it be delivered and assembled by the pros. But those who are handy may wish to save some money and order an outdoor storage building kit that comes with assembly instructions.