I've plugged up the ammo drum. Started the morning watching the movie Mr. Deeds while putting together the handle fixtures. It's made of 8x layered cardstock with notches etched through 70% of the thickness to allow for bending. It's like having a mitered set of plates to fit together, but with the top layers continuous to allow for greater rigidity. I elected this method than having separate sections cut to fit for lamination as it allows less measuring and fitting. It also lets me saw things apart with that nice sadistic glee you get from hacking something apart.
Anyways, I've shifted mediums for additional rigidity. Using 1mm thick cardboard from the back of sketchbooks for the ammo drum face, I can achieve greater strength than Magic: The Gathering cards laminated to fit such a large surface. (A card takes up about 62mmx88mm, and the circle diameter is 73mm, so I'd have to make a new composite just to fit the area, which is fairly risky.) However, Magic cards work just fine for the handle. I'll have to reinforce the sides and joints to allow the handle to support the massive load the 20+ sheets of cardstock now place.
Missing parts: Foreward and aft handles, ejection port cover, back and front conical drum covers, and the fairly useless pipe underneath.