I finally bought the kid's undies pattern from that*darn*kat that Dawn blogged about and made my first pair. They're so cute!!!
These are made out of an old T-shirt, and some of the red cotton/lycra from this top. I ended up sewing them entirely on my sewing machine, not using the serger at all. There are two rows of zigzag because when I did the first topstitching I started too close to the seam and had to do another farther away!!! But I actually like the look.
I'm definitely making more of these for DS1. This first pair is actually size 2, which I did just to see how it went. Maybe if DS2 starts potty training soon he can wear these! One can only hope!!!