I am currently prototyping a sock design using DK yarn (all I have) and so it will be hard to try on as such but at least I can see if it works as a stitch pattern / design. I am also contemplating frogging a hat I rarely wear that is made of Wendy Happy (sock weight / 4ply yarn) so that I can use it to prototype socks that I could actually try on. This one may fit an elephant, maybe Shrek or possibly some kind of giant.
ETA: I have found some Patons 4 ply 100% cotton in my stash (that could do with being better organised even if it is not that big) which will not make comfortable socks (it is a bit shiny and harsh) but will at least make socks the right size to try on! Now all I need to do is to decide what stitch patterns will work well together because my first attempt in DK yarn has just been frogged!