Shelley at How Does She? posted her tutorial for these DIY thing 1 & thing 2 costumes which have me seriously wishing I had twins to make these amazing costumes for!! She said the striped leggings were actually women’s socks that she just cut the feet off of and the onesies were ordered from Ebay, but what absolutely makes the whole costume so great are the wigs she created by hot-glueing a blue feather boa to a babies knit cap!
See the full tutorial with pictures at How Does She?