Each of these is made from too-small T-shirts and other jersey remnants I had laying around. The fit is not perfect, since no prior measuring took place. But, I think they look really cute. Yanic's is full of Tarantulas from an old shirt my parents gave him a few years back. And the girls' is just an assembly of bright colored jersey knits.
I did not come up with this great idea on my own. Have you heard of So You Think You Are Crafty??!! It's awesome. You need to check it out. They are currently in season 5 of several ladies competing against each other every week with a new craft. Typically, all the Ladies will post tutorials for their respective crafts.
Last Season, Cheri from "I am Momma - Hear me Roar" participated with these awesomely cute hats. You will find the full tutorial over here.
She has a lot of other great tutorials as well. Make sure to check them out.