A modular enclosure may include a number of interlocking components, such as panels, that may be interconnected to form sidewalls, roof and/or floor. The panels may be constructed from blow-molded plastic and a first pattern may be disposed on one surface and a second pattern may be disposed on an opposing surface. One or more points of intersection may be located where the first pattern and the second pattern overlie, and a depression may be disposed at the points of intersection. The depressions are preferably sized and configured to increase the strength and/or rigidity of the panel.