Abstract: The production of high precision molds and castings for dental prosthesis and the like is enhanced with a casting ring and sprue former base constructed of a clear expandable thermoplastic. The ring and base are telescopically interlockable with each other to define a vessel containing a mold form strategically disposed therein so that as investment solution poured throughout is able to cure without detracting from the precise measurements of the mold form to provide a true mold from which precisely dimensioned castings are formed.

Abstract: An apparatus for making ice cubes includes an ice cube tray and an inner grid core. An outer grid core for the apparatus includes sloped sides and a threaded opening at a top of the outer grid core. The outer grid core is wider than the bottom of the core. Dividers are positioned in the ice cube tray and are upright with respect to the ice cube tray. The dividers are inserted into the inner and outer grid cores. A threaded stud is engageable with the threaded opening in the outer grid core.

Abstract: A pair of diametrically opposed protuberances, comprising inwardly projecting bumps, extend from the otherwise smooth surface of opposite corners of adjoining side walls of the generally cubical pockets in an ice cube tray. These protruberances, define stress concentration areas at the corners of the frozen cubes which, when the plastic tray is twisted to release the cubes therefrom, cause the cubes to fracture and alter their configuration to the extent that they are prevented, either because of their enlarged outward dimensions or because of ice particles that have flaked therefrom and are in an interferring position, from being reseated in the tray in the as-molded position. Thus, each cube remains elevated from its original position with the side walls of each cube spaced somewhat from the side walls of the mold for relatively easy individual removal.