They use a multicolored yarn in medium weight, but you could also make them a stash-busting project and use all the leftover bits of yarn from other projects if you don’t care much about them matching.
Because there isn’t elastic in them, they might not hold themselves up on your leg, but you could work in some elastic at the top if you wanted. Or wear them over leggings.
You can grab the free pattern from My Poppet Makes.
[Photo: My Poppet Makes.]