Stock

A game owns the mints it uses. A mint in the game's stock is out of your bag and the game's to place: as many instances as you like, in any room of the game. It comes back to the bag only when no instance of it stands anywhere.

eggox bag                   the mints in your bag
eggox stock                 what the game holds, and how many stand where
eggox stock add "Lamp Post" a mint from the bag into the stock
eggox stock take "Lamp Post" back to the bag (nothing of it may stand)

In the Studio the same happens by dragging from the bag into a room, and the STOCK section of the hierarchy shows what the game holds.

A thing named in a room or in things/ must be in the stock. The push refuses otherwise and names the file. The art of a thing is the mint's; the folder only names it.