It rains a lot up here in Northern California. Which means you really need a good pair of rainboots, sneakers just aren't gonna fly when there are puddles the size of a small pond in every parking lot. The thing with rainboots, though, is that they're like little refrigerators for your feet. It also gets really cold up here in Nor Cal, so that can be a problem, too. I've seen boot liners, but they're not that cheap. I've seen tutorials for making your own out of felt, but I don't have any felt.
I do have a felted wool sweater, though. So here's what I did...
Makeshift boot liner on the fly:
1. Felt a wool sweater by washing and drying it (mine was already done--thanks for accidentally ruining your sweater, Danielle)
2. Put your foot into the arm hole (I put mine into the top of arm, by the arm pit) until it gets too tight to go in further
3. Cut the arm of the sweater off, then do the next foot in the other arm
4. Once you have your feet in the arms of the sweater, cut off the remaining excess fabric so it is the size of your foot.
5. Sew the toe shut if you wish. (I didn't, because I was rushing out the door to head down to San Francisco and the airport)
6. Voila! Toasty feet.