As I model in the era where 20-footers would have been even more dominant than 48's, I've been trying to develop 20-footers using cardstock. My most recent draft is below; I'll tell you, those ribs are not easy to get across in cardstock. Although the containers do look better in person than in the photos. If anyone has any suggestions, please feel free to espouse some wisdom. This is a farther back view, and also shows a 48-foot container I designed today for a fellow modeller's intermodal company (JENSON).