Abstract: An engine includes a plurality of vessels coupled to a rotatable frame and arranged about a center of rotation of the rotatable frame. Conduits connect pairs of vessels to allow mass to move between the pairs of vessels to generate a gravitational moment about the center of rotation. Each pair of vessels can have a pathway for conveying fluid heated by a heat source. The pathway extends from the heat source to a lower vessel of the pair, and can further extend from the lower vessel to an upper vessel of the pair. The pathway can be configured to expand volatile material in the lower vessel to tend to push the mass from the lower vessel into the upper vessel, and to contract volatile material in the upper vessel to tend to suck the mass into the upper vessel from the lower vessel. Vessels can be controllably connected to pressures to move mass via controllable pressure and temperature distribution systems.

Abstract: Disclosed, amongst other things, is: (i) molded article holder (450) having a retainer (480) that is snap-engagable with an insert (470); (ii) a retainer (480), for a molded article holder (50), that is snap-engagable with an insert (470); and (iii) an insert (470), for a molded article holder (450), that is snap-engagable with a retainer (480).