Abstract: A foldable stool has trapezoidal sides including first and second nonfolding side walls and first and second folding end walls. Each end wall includes first and second nonfolding half-walls and a piano-type hinge connecting these half-walls to each other. A folding top wall of the stool includes first and second nonfolding top half-walls hinged together with a piano-type hinge. Piano-type hinges connect each first half-wall to the first side wall, and piano-type hinges connect each second half-wall to the second side wall. A lip portion extending horizontally outwardly from the top wall when the stool is in its upright condition is in contact with the upper edges of each of the side walls and end walls to support any weight put on the stool along the entire top edges of these side walls and end walls.