A multi-layer rotational-molded plastic article has an area, such as a sight line for viewing content levels, where an inside layer protrudes through the outside layer and may be bonded to it. A first flowable material such as plastic resin is introduced into a mold having an insulating member extending through an aperture or slot into the mold. The mold is rotated and heated to less than full cure. The insulating member is removed, a second, transparent flowable material is introduced into the mold, and a cover member replaces the insulating member. The mold is rotated and heated to cure both resins, and only then cooled and opened.