Adventures of a Middle Sister: DIY Tie-Dye Swimsuit Cover-up. Plain white oversized T-shirt, tie-dye kit, scissors, needle & thread. Could use a T-shirt that's already colorful and skip the tie-dye step.
DIY Draped Skirt…no sew. The girl in the pics is actually using an old H scarf, but any jersey fabric (roughly wide and long) will do. Just wrap, twist and tuck (and maybe add a safety pin to keep it all in place!