Abstract: Modular building panels having foam cores protected by metal skins are releasably interconnected in edge-to-edge relation to one another. The interconnection is accomplished by bending the metal skins that protect the top and bottom surfaces of the core into complementary shapes so that contiguous panels are snap fit together when the bent metal skins are interlocked with one another. In some embodiments, the cores are grooved and the flexibility of the interlocking members is increased by decreasing the depth of the grooves and the flexibility is decreased by increasing the depths of those grooves because decreasing the groove depth provides less support for the interlocking members and allows them to displace more during the interlocking procedure and increasing the depth increases the support and thus limits their movement.