JSON-defined items have their own defined weight. So if you make an item that unfolds into a 50x50 vehicle made of heavy duty frames, you can still make it weigh nothing.
When you fold it, the code adds the weight of all installed items; so the individual parts of the unfolded item is greater than what the defined item had.
You can still unfold it by standing on the item and pressing Shift+a.[/quote]
shift+a did not work 
I have nothing in my hands but does nothing 
I get text thats says
You do not have that item.
But I am standing on the folded deployable survivers station