The DDU, as designed by Fuller, did hang on a central mast. The outer wall was not load-bearing. The central mast carried the load through cables that held the suspended floor. Fuller worked with Beech Aircraft in fabricating the prototypes. Beech would have been the principle manufacturer, had Fuller finalized the design. In business, he was his own worst enemy.
The Qube, in Vancouver, Canada, is built using similar techniques to Fuller's earlier Dymaxion designs.
https://en.wikipedia.org/wiki/The_Qube_(Vancouver)