PVC pipe and sheet can be cut with standard tools, can be heated to form and bend it, and is available in gray as electrical conduit. Soften it with a torch or heat gun, using a torch takes a light touch to keep from scorching it light scorching can be sanded off), formed with a gloved hand, and set once in shape with a spritz of water. It is cheap enough to play with and a few dollars gets you a 10' length that will sheath a fair collection.