Hi Ashlee,
When my kids were babies, I took my husband's old knee high socks, the ones headed for the trash when he wore holes in them, and cut off the "tube" part, and slipped it over their legs if they crawled around w/out pants, which the girls frequently did when they were in shorts or dresses.
If you find that these are too big for your baby, get women's crew socks from Hanes or Fruit of the Loom, and use the tubes from those. Cheap enough for a 6 or more pk. that you can cut them up and not feel too bad about it.
For extra padding, you can fold up the remainder, and tuck it inside on the kneecap. That way, none of the sock goes to waste and they are nice and cushiony! Voila! Baby knee pads.
HTH! :o)
K. W