Abstract: A frame structure for a container or box includes panels with frame bars with flanges that overlap with the panels, a corner piece at each corner and bolts connecting the corner pieces to the ends of the frame bars, each corner piece including sections extending in planes that are angled to each other, each section positioned flush with a frame bar end and having a through-hole, with a bolt through each through-hole, perpendicularly to a plane of a respective section, in a longitudinal direction along a respective frame bar and into a respective hole facing an end of the frame bar, and fastened in a hole of a cross-dowel located in a seat in the interior of the respective frame bar, each cross-dowel being cylindrical and having a groove in at least one end, the hole of the cross-dowel being aligned with the hole facing a frame bar end.