Cap that baby off with a sheet, and I've used a three or four mil ply that was hanging around the workshop like a bad smell. Works surprisingly well with pop-rivets, which end up as flush as those on a Boeing Dreamliner.
Right on cue the metal-sheet guy calls. "Hello metal-sheet guy" I say jocularly as you would to Postman Pat. But it turns out the sheets that will make up the sides of this module are ready... watch this (aero-) space.
