This short collection of projects - some useful, some instructive, and some amusing - can be made for around 10 UK pounds (16 US dollars). The estimated cost does not include an enclosure (box). All of the projects are battery powered, so are safe to build.

An intriguing and novel way in which you can tick-off time passing!

This project describes how you can build an accurate low-cost electromechanical clock, using the minimum of component parts and normal household tools. The Cardboard Clock uses a simple battery- powered circuit to control a pendulum and thus turn three gear wheels which double as “time dials”. There are just five moving parts, including the cardboard gear wheels. The clock keeps time to within 15 seconds a day.