Somewhere in the Grand Museum, at the heart of the Chaos of the Imagination...
There is a place.
It's a small place. It's a large place. It's a dark place. It's a bright place. For that matter, it's whatever place you think it is, because in the Theater Of The Mind (or TOTeM for short), anything and everything you can think of will instantly become manifest and solid.
The Theater of the Mind is at the exact center of the Museum. It could be considered the Museum's central processor, or its soul, whichever you prefer. Access to the Theater is not immediately obvious. The Curators know, but they aren't telling...
Thoughts are fleeting, and if you leave a thought alone in the Theater, it will fade away. If you take one with you, it will be just as real as if you had built it yourself.
Unlike the Mess's Instantiator (see the Newbie Guide), the Theater of the Mind is not limited in terms of what levels of craftsmanship and complexity it can handle. That's how the Curators like it, since creative ideas and thoughts are the mental building blocks from which new artworks are made. If you have the mental discipline, then anything you can think of, you can make.
Or unmake.
Including yourself.
If you don't have the mental discipline, then may the Box have mercy on you.