An inexpensive, insulated, upright wall, ceiling, floor or roof, made of panels fastened together at panel edges. Each panel has a can backing and supporting element (preferably masonite, but alternatively plywood, plastic, metal lath or the like), panel-reinforcing bars connected to edges of the can-backing element, a plurality of layers of randomly-placed cans on the can-backing element and within the bars, and a can supporting and stabilizing element on the side of the cans opposite to the can-backing element. Saving labor of more careful arrangement of the cans, and increasing the strength against breaking of the panel, they are heterogeneously dumped into the frame of the bars and the can-backing element; and preferably the frame is shaken to somewhat settle the cans in it. In further stabilization of the cans in place, preferably porous, insulating concrete material, or foamed concrete, or foamed polyolefin plastic material is placed on top of the assembled cans. The outer can-supporting element may be unitary--a panel surface formed of this concrete or foam-plastic material--but preferably it is composite and includes this material and other panel-surfacing material, such as a sheet of masonite, plywood or celotex, applied while the concrete or foam plastic is in pasty or fluent condition, adhering to the concrete or foam plastic. Optionally the cans may be glass bottles or jars, but preferably they are used cans of the beer or soft-drink type. Optionally: the concrete or foam-plastic material may be metal-reinforced; the side bars may be of wood; the frame, into which the cans are dumped, may be a box of molded plastic; or the cans may be dumped within a can holder, temporarily positioned within the outer frame, this holder being withdrawn after the concrete or foam-plastic material is poured on top of and within spaces provided by the filler, the sides of the assembled cans, thus forming a plastic-material outer can-supporting element and associated side bars. The wall may include exterior masonry units, siding, or stucco.