Who would of thought you could have so much fun with just a few shiny magnetic balls.
Not just a puzzle - I bought 2 of them, mashed them up into a ball and now I use them like a stress ball. I grind, squash, squeeze, tease them apart, wrap them around my fingers and annoy the hell out of people. I haven't had the time to play around and make shapes yet I am too busy making sculptures by pressing them into shape.
The magnetic strength is good, but if putting them in a single chain, be careful that the hanging weight may exceed the magnetic force and drop to the floor. They should stay together, but there is a risk of a few breaking free and straying.
As with any toy, be careful around kids and animals that may want to eat them. The results could be disastrous.
The magnetic field is not very big, but care still needs to be taken near magnetic sensitive cards and equipment etc.