I used a heat gun to make the sides slip right in the latching plastic bottom.  It was together in no-time, flat. Because I modified  the container a little with an underneath  Plywood sheeting and 3 inch Castors, I can roll it where I want on my Huge Patio.  Had a big storm come thru and no water was left, inside. Totally Dry.  Lid Hinges work Great and makes the lid, fit snuggly and smooth with no slamming. That is a Great Safety Feature, too.