Does this even need words? It is so simple it is genius.
You need a pillow case and an embroidery hoop and that. is. it.
What a fast way to catch the dirty clothes my darling daughter strips off every ten minutes? Currently hanging and working a charm near the door of her bedroom. Want to mix it up? Change the pillowcase easily to wash it or give it a whole new look.
Simply Genius 2 Minute Pillow Case Laundry Hamper DIY
Undo your embroidery hoop so you have the smaller hoop in your hands and insert this into the opening of the pillowcase, slip the larger hoop on the outside sandwiching the pillowcase and tighten.
Hang up on a hook or a doorknob or you could get fancy and add a pretty ribbon or rope from the embroidery hoop. See similar laundry hampers here.