Ironically, on the RL page is presented this:"Considering that atoms are mostly empty space, and only feel solid due to the strong negative charge present on their surface (such that it is) which repels other atoms in a similar manner to what happens when you try to touch the south poles of two magnets together, ordinary doors are technically examples of this trope."
Absolutely and mind-blowingly (IMO) true. Matter is, for all practical purposes, space. The matter within an atom is mostly space, and the matter within the atom's nucleus is mostly if not totally space. Electrons are basically just a force shield, thus mostly if not totally space.
A pea in an NFL stadium would represent more matter per cubic measure than space. And in this analogy, the pea would also be basically space.
So a door made of steel, platinum, invulnerbilium, or whatever, would be a force shield with its own self-contained power source.
And you and I and our not-brothers are all made of force shields, of space.