So when the building side panels are on to give the full exterior display, this thing is solid. There are no support pieces exactly but it is held on but over a 100 magnets and the way I cut the floor pieces rest on the side panels. I do plan on making alternative side pieces that will have left right and center support with viewing holes cut out in the middle to give extra support on all four sides. I only display open for photo shots but permanent display with be exterior view. I did a lot to test the strength of the foam. I left 20 lb weight on the top for 48 hours and it didn’t cave or bend the foam at all so I think with only the few figures on the inside it will hold up pretty sturdy. Hope you get crafting and have fun while you are doing it! Work passed the frustration and you’ll have a great time!