Finally: The Apartments
Near the center of the room is the Apartment Building.
This may be built from a single shelving unit, or may consist of several.
Each shelf is at least 30" wide, 50" tall and 20" deep, supporting 5 stories of miniature apartments.
The apartments are little ten-inch cubes, with a walkway along each side.
(The shelves can have strings of lights along them, powered by battery packs.)
On the ends are elevators, which visitors may operate by pulling a string.
Above each apartment is a small sign with the apartment number and an artist-written description of what is inside, along with some details of the world-building behind it.
Some alien creatures ("Wanderers") are on the walkways instead of inside their apartments. Their position and location can change from day to day.
At first, viewers see the mostly-closed-off outer side, peering in through the windows.
As they walk around it, they can see that the other side is open like a dollhouse.
The shelves are wrapped in clear marine vinyl for protection.
(This is what the Stopwatch Time Machine means by the "transparent film of the time-pausing effect.")