A modular sign including a spacer assembly affixed to graphic panels is provided. The modular sign is movable between a knock-down configuration and an erected configuration. In the knock-down configuration, the spacer assembly lays flat on a back surface of the graphic panels. In the erected configuration, the spacer assembly is positioned behind the graphic panels so as to provide a support structure for the graphic panels while simultaneously being at least partially concealed by the graphic panels. The modular sign is moved from the knock-down configuration to the erected configuration by rotating the graphic panels up and away from a flat surface and is secured in the erected configuration by inserting a key flap into a keyhole. Once the modular sign is in the erected configuration, it can be installed onto a tube and/or another support structure, such as a register sign.