This Instructable covers the basic all-fleece version I made for Corvidae as she was starting to walk. It's warm here in the dry season, and while I like for her to go barefoot, the playground surface and sidewalks would simply get too hot in the summer sun for bare feet. I started making these simple booties out of scraps of old fleece blankets, and was incredibly happy with the result for several months, an eternity in baby gear.
As her feet grew and she started putting serious miles on every day, she also started wearing through the fleece in just a few days so I changed up the pattern a bit and added a vinyl or leather bottom to the fleece bootie. That v2 shoe style is still going strong at age 2.5, and is proving even more cost-effective: check out the Instructable here.