An Estateverse is a type of verse created by an unknown species. They are simple 3 dimensional voids, but come with a cache of materials that allow you to make planets, stars, black holes, galaxies, and a Celestial Core if you buy that extra. They also come with a machine that allows you to simulate the creations, and then build them. They are valuable to advanced civilizations due to allowing a very large area, that is easy to build in.
The Estateverse comes in Tiny (500 Million LY in area), Small (750 Million LY), Medium (1 Billion LY), Large (3 Billion LY) XL (10 Billion LY) XXL (100 Billion LY), and XXXL (1 Trillion LY). The bigger the Estateverse, the more materials the cache contains. There are also shops to buy expansions and extra materials for your Estateverse.
Estateverses are usually only sold to leaders of civilizations, as a residence, or entities that want to feel the power of ruling over a verse. The tiny Estateverses have more room for bargaining, however, and can be bought by anyone with enough money. Tiny ones are usually used as a "sandbox".