A novel bed frame is assembled by sliding the ends of hollow metal bars into narrow slots cut into other hollow metal bars. A first bar has an L-shaped first slot. A second bar has a U-shaped second slot and L-shaped third slot, both spanning two adjacent sides of the second bar. An end of the first bar is inserted into the U-shaped second slot, whose width is less than twice the thickness of the metal from which the first bar is made. A portion of the L-shaped first slot aligns with a portion of the L-shaped third slot when the first bar slides into the U-shaped second slot. The top of the third bar is inserted into the aligned first and third slots. The first bar is a longitudinal bar, and the second bar is a lateral bar of the bed frame. The third bar is a support leg.