Removing the two front hinged panels and lifting the back panel reveal a tray ready to house an 8-, 10- or even a 12-column Comptometer. It appears that the tight locked surfaces and heavy paneling could well support the weight of machine and tray. The tray with Compt would just be pulled up the narrow sloping side ramps to the front position, the rear panel locked down, ready for operation. The reverse procedure would then hide it all away, restoring a flat surface ready for shuffling papers, etc. As David has aptly commented, "nifty".