An electronic interval timer in a dodecahedron case is described. The timer is set by turning uppermost one of 11 faces; and reset by turning uppermost the 12th face. In one embodiment, the timer is free of buttons, knobs, springs, time displays, electronic visual indicators and openings in the case. Time interval completion is announced via audible tones or speech. An aggregate time interval may be set equal to the sum of legends on more than one face. The timer detects carrying such that a running time interval is not modified. The timer may be programmed via a sequence of uppermost sides. Modes may be selected via shaking or tapping. Time remaining may be announced, an interval cleared, or an interval restarted responsive to detected motion. Other polyhedral shapes may be used. Claims include a method of setting a time interval; and specific ordering of face legends.