There was a proposal to build a freighter version of the A380, but no buyers. Proximate reasons: the A380 is a triple-decker, with two floors designed to suppo

There was a proposal to build a freighter version of the A380, but no buyers. Proximate reasons: the A380 is a triple-decker, with two floors designed to support the weight of seats and passengers, not cargo containers. Some reinforcement would have been needed, adding to the airframe weight. Additionally, the flight deck is on a mezzanine level in front of and between the two passenger decks -- right where the 747 freighter has a lifting nose door. So the A380 cargo mod would have required side-doors (which is okay, that's how most freight airliners work), and at least three of them -- one per deck -- which would have entailed cutting big structurally reinforced holes in the fuselage, adding more airframe weight, which was not okay. By the time they'd done the sums, the design compromises would have made the A380 freighter less efficient than buying a pair of A330 freighters, or using the barely-smaller 747-8 (which snapped up the next-generation jumbo-sized freight market but sold very few passenger aircraft because the A380 got there first).