If you are interested in paper engineering or paper automata, this is a great value. It's also a great way to break into automata, requiring few tools and relatively little time.
The first is the gear model that uses only cardboard to make a fully working mechanism with two gears.
The second model is a working set of bevel gears made completely from card-stock paper.
Pump the paper bellows on the third model and the rotor spins.
Head over the download section of Flying-pig.co.uk to check out this multi-pack kit and a ton of other well-designed paper automaton kits.