Abstract: A telescopically adjustable structure capable of defining or measuring an arbitrary three-dimensional volume and having twelve telescopically adjustable telescopic units, capable of maintaining a change in telescopic length and eight corner connection units for assembling the telescopic rods into a three-dimensional structure. A method of assembly may have the telescopic units adjusted to specified length prior to three-dimensional assembly or, alternately, the telescopic units may be assembled in collapsed telescopic form, and adjusted in assembled fashion. Particularly suited to provide a lightweight, low-cost, low-damage furniture or object double to check how the furniture volume might fit in a space or be transported to a space.