I found this site a while back and fell in love with some of the cool toys he's created. Calling it "Toy a Day" is quite a misnomer because he often goes weeks in between new toys, but hey, they're free so I can't complain too much.
These toys are pretty easy to put together, although I would imagine they might be too difficult for kids without their parents' help. Some of them require pretty precise cutting and taping or gluing. However, the author said in his latest post that he's releasing a new design that won't require taping or gluing, which sounds pretty sweet!
There's a good mix of characters that appeal to both kids and adults, so it's fun for everybody, especially a nerd like myself! He even occasionally includes celebrities or political figures, which is pretty cool. I definitely recommend checking through the archives- there's something there for everyone. He even gives away a blank template so you can make your own if you're more artistically inclined than me.