At maker faire SF there was a $10-$15 kids plastic watching making kit some association was selling. Search for Horology, AWCI (http://www.awci.com/). I have been obsessed with lego-based pendulum clocks for a while as well as how cuckoo clocks work.

This is the kit I saw btw (not sure about this particular seller): https://www.happypuzzle.co.uk/products/the-amazing-clock-kit...

I will pick one up for my kid when she grows up :)