An apparatus (21) for assembling a collapsible enclosure assembly (1) onto a container (11), the enclosure assembly (1) being of the type comprising a plurality of collapsible walls (2, 3, 4) and which is adapted to be supported, when erected, on the container (11) so that in situ the enclosure assembly (1) encloses a region above the container (11), the apparatus (21) comprising means to move a collapsed enclosure assembly (1) from a storage position (25) to an assembly position (36), means to move the walls (2, 3, 4) of the collapsed enclosure assembly (1) when in the assembly position (36) relatively apart to expand the enclosure assembly (1) so as to be of generally tubular form, and means to mount the expanded enclosure assembly (1) on a corresponding container (11). A method for assembling a collapsible enclosure assembly (1) onto a container (11) is also provided.