A pallet cap for covering and connecting with at least one existing pallet includes a reinforced platform having a flat top surface and a bottom surface opposite the top surface. Four vertical, peripheral edges connect the top and bottom surfaces. Three or more of the edges form at least one edge extension continuing outward from the reinforced platform, and at least one edge notch proximate the edge extension and recessed from the edge extension. At least one notched corner is formed by distal edge extensions of edges meeting perpendicular to one another. A plurality of retaining walls extend downward from the bottom surface of the platform and define the edge notches, proximate a junction of the platform and the edge extensions, for securing the pallet cap over a shipping pallet. Multiple caps may be connected to form an expandable raised flooring system or other structures.