Abstract: This chassis has side, top, bottom and rear plates which are made out of sheet stock and where are oriented at 90.degree. with respect to each other. Bifurcated tongues are formed in edges of plates. Elongated slots are also formed in plates at points spaced away from the edges thereof. The slots and tongues are dimensioned and oriented on the plates such that in an assembled shelf, the bifurcated tongues are located in associated slots so as to form square openings defined by walls of the associated slots and bifurcations-openings. Self-tapping screws threaded into the square openings and axially aligned bifurcations-openings cut threads in the walls defining these aligned openings over the full grip length of the screws to hold the plates together.