Wheel and Slide Timer
See through perspex timer with coloured liquid. Turn it one side up and the liquid drips down and turns a wheel - turn the other way up, and the liquid drops down a zig-zag slide. Not a timer that measures a specific amount of time, but one that is great for managing "turns" for children, or just watching to relax for a little time-out. Approx 12 cm high by 5 cm wide.