Step 1: Gather your supplies
I found a 100% wool sweater and washed & dried it several times to felt it. The fibres seized up and got worked together so tightly that it really changed the texture of the sweater completely. The other sweater was wool, but the percentage was unreadable (old sweater, old tag) and it did not felt at all. As you'll see, I used the thick and plushy felted sweater for the soles, and the other wool sweater for the uppers.