Kitchen Sink. Three shelves held up by screws and coat hangers. The small screw connections at the wall are well-modeled as pin joints. Viewed from the side, this 2D truss has 6 bars (3 shelve & 3 coat hangers) and 7 joints (one at the front and back of each shelf, and one at the top), and 8 reaction forces (2 at the wall end of each shelf and 2 at the top of the top hanger). Thus, the "rule of thumb, number of equations equal number of unkowns" formula works: 8 + 6 = 2*7. But this truss is not rigid if not connected to the wall. The rule of thumb for "rigid when unconnected" does not work: 3 + 6 < 2*7. Truss assembled at 227 Bryant Ave, Ithaca, NY on 9/15/02.