Homemade spider jockey costume (a composite Minecraft monster consisting of a skeleton archer riding a giant spider). Kid-sized, built by Katie (I assisted, mainly with painting, but the design, planning, and most of the construction was her).
Mostly cardboard, covered with paper to smooth it out and provide a painting surface. Heavy fabric and dowels to form the frame for the center of the spider body, with paracord to hold the legs on. For the skeleton: felt panels, some pinned to a black shirt, some to the suspenders. Which, incidentally, were made from old Comic-Con lanyards.