Sew, sew again.
It’s 100% Cotton (other than the trim and Velcro anyway) and machine washable. The inside is basically just absorbent cotton flannel. One solid piece on the underside, with several smaller blocks inside for absorbency, topped with a cotton print fabric (there’s actually glitter on the green fabric but hey, at least it isn’t pink…) Then I added the Velcro strips and used a satin ribbon to trim the edges and give it a finished look.
And tomorrow, sock in progress pictures! Since I’ll just deal with being productive at night for now.