When I was a young kid, my younger brother and I used to use the cut-off bottoms of egg cartons as hoards of Daleks (the menacing robotic beings from the BBC's Doctor Who TV show which I have to say has rather taken a step backwards under Chris Chibnall's leadership - not because the Doctor is now a woman by any means - I like the new Doctor - but because we get fewer episodes and only every other year, it seems. Shameful!).
This author is much more inventive than we were, and this book was a great idea. With the ideas colorfully illustrated and explained in detail - but simply! - kids can end up creating a large variety of neat little toys from animals (chicken, bee, hedgehog, tortoise, octopus, bunny, and others) to vehicles (dump truck, fire engine, pirate ship and more), to flowers, face masks, treasure chests, rockets, and on and on. This will keep a kid occupied and render you broke buying enough eggs to generate all those cartons! LOL!
But approached as a bi-weekly project, once you've used all those eggs, it can be a cheap and fun way to spend your time, especially if it's raining or cold out. They may need some supervision depending on their competency and trustworthiness with glue, paints and scissors, but it's worth it to see their joy at making something themselves - something fun and practical - boosting their self-confidence and getting double the return - time well-occupied making a toy and then more time well-occupied playing with the toy! I commend this as a worthy tool to a child's happiness.