Utilizing steel shipping containers, modular buildings are composed of a roof panel, floor board, corner posts, and wall panels. The lightweight yet strong components of the shipping containers facilitate modular design and manufacturing that are perfect for low cost structures that can be assembled in seemingly no time. Flat pack containers meet the structural standards of a wide range of international governing bodies. All other components of the buildings are installed at the construction site. Wall and roof panels, windows, doors, and joint fittings will be packed within the containers before shipping.