Abstract: Polystyrene beads or beads of other thermoplastic material are expanded to a consolidated foam structure in a hollow cavity of a marine float or other structure by providing the beads with a uniform coating of a saturated brine solution or other aqueous solution of water-soluble salt and exposing the solution to microwave energy to boil the solutioln and thereby heat the beads to cause expansion and fusion to a foam structure.

Abstract: Floating structures, for example, for recreational aquatic activities, comprises a plurality of individual uniquely-constructed modular flotation units constructed to permit any desired freeboard dimension and/or buoyancy characteristics.

Abstract: An etch timing device for timing the etching of aluminum products and the like includes support members for supporting aluminum foil therebetween in a bath of etchant, the aluminum foil having dimensions corresponding to the quantity of aluminum to be etched in the bath. One of the support members is in a fixed position while the other is movable vertically relative to the first member. The movable support member is connected to the lower end of a rod which is slidably mounted in a hollow elongate body member mounted in association with the bath. The upper end of the rod extends above the height of the body member when the aluminum foil is supported and includes a visual indicator and stop means, typically a ring integrally formed with the upper end of the rod. When the ring moves downwardly upon dissolving of the aluminum foil, this provides a visual indication to the operator that the required etching has been completed.