I made these in about twenty minutes (each), and I hand-sewed them. I got the idea from the book Super Crafty, which is a wonderful book! I had several old sweaters that I loved but that were either too small or pilling in certain areas...so now I get to wear them as hats! The little appliques are so fun to make, too. It's a great project to do in front of the TV
Here's a written and hopefully understandable tutorial (I don't have pictures of me making the hats!):
1. Lay the sweater on a flat surface, smoothed out
2. At the bottom of the sweater (the nice, hemmed part), measure a half-circle that's 11 inches long and 7 inches high.
3. After you mark the measurements, it helps to draw the semi-circle with tailor's chalk or something before you cut it out.
4. You can either cut through both layers of the sweater, or just cut through one layer, turn the sweater over, and remeasure and cut.
5. Put both pieces right-sides-together, and sew. I hand-sewed using a blanket stitch, but if you plan to throw it in the wash, you should probably machine-sew it. And because you're using the bottom of the sweater, you don't have to hem the bottom of your hat!
6. You can decorate by adding bias tape (like I did on the zebra hat), felt appliques, buttons, ribbon, rick-rack...anything you want!
I hope that's clear. Let me know if you have questions.