Step 2: Build the base. Now you’re going to build the base of your shed. We used pressure-treated wood for the base since it was the closest to the ground and the most likely to be exposed to the elements. Create a rectangle in the dimensions of your shed (again, ours was 72 in. x 36 in. – our only goal was to fit the lawnmower inside, so we ke Unfollow rubbermaid shed shed to stop getting updates on your eBay Feed. You'll receive email and Feed alerts when new items arrive. rubbermaid shed shed: Items in search results. 4' x 6' Large Roughneck Vertical Storage Shed.