Climber Rob
Human
My bad. I guess they must be lying in their marketing literature “Everyone associated with Four Wheel Campers is grateful that the company developed a pop-up design and standardized on welded aluminum frames.” https://fourwheelcampers.com/company/our-story-the-history-of-pop-up-truck-campers/
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The upper part of the frame is welded aluminum. The lower part of the side walls and the floor is plywood. They have been making them like that for a very long time. Here's a picture of a new frame, which looks a lot better than the old ones. The entire lower dark grey section is plywood.