Concrete Block Foundation
Concrete blocks offer the best foundation option for a temporary shed. They can be set on bare ground, without digging or major disruption of the soil. They can support either big beams or skids, for a portable shed, or a solidly-framed floor, for a shed to be dismantled. Either type requires a solid floor, framed with pressure-treated 2-by-4-inch framing lumber and covered with plywood, which can be moved or taken apart easily.
Simple Walls
Basic walls should be framed with 2-by-4s, but covered with a sturdy material that either can move or come off. The best choices are 4-by-8-foot plywood sheets or corrugated metal, either aluminum or galvanized steel. Both materials can be attached with screws for easy removal, but are weatherproof and strong enough for a solidly-supported portable shed.
Simple Roof
A simple roof is best for a temporary shed. The easiest style is a shed or pent roof, which slopes in only one direction, so it does not require complex rafters or trusses. It can be framed with 2-by-4s as common rafters, usually from front to back, and covered in corrugated vinyl or metal, which can be moved or removed easily.
Location
Location is important for a temporary or portable shed. The site must be solid enough to support the shed and its contents, but easily accessible for a forklift for portability, or a truck or trailer to remove material if the shed is dismantled. Taking a temporary shed apart is just like building it in reverse. Remove the roof, then take off wall siding, take the walls apart, dismantle the floor and get rid of the concrete blocks. Build a temporary shed with screws rather than nails, which are easier to remove.