First you start out with a pair of knee high socks. These are girls socks but the adult ones work great too.
Then you cut off the heal and toe of the sock.
Then you fold over the "foot" piece so that it is right side up
Next put the folded piece over the leg part of the sock and line up the seams.
Sew then together on your machine with a straight stitch. I tried on one pair a zig-zag stitch and it made the seam pucker.
Now unfold the seam and you have some cute baby legs for your baby or toddler.
The finished product on Baby Sister.
Here are a few others I made: