A grid resistor has a plurality of identical resistor support frames each defining a plane. The frames are stacked in alignment to form a hexahedron structure with levels of frames. Plates on the outer face of the hexahedron structure support the frames tightly against each other to maintain the hexahedron structure. Within each frame there is at least one ribbon of resistance material which is fanfolded providing a plurality of equally spaced, parallel, uniform linear lengths connected by U-shaped folds. The U-shaped folds have studs at the outer tips of the folds which engage holes in the resistor support frames. Bus bars selectively couple the resistors in each level to a pair of output terminals.