Portable hole

A portable hole was a magic item worth 20,000 gp consisting of a circle of black cloth about 6 ft (1.8 m) in diameter that, when spread on any surface, opened an extradimensional hole to a non-dimensional space that was 10 ft (3 m) deep. When not in use, the hole could easily be folded to the size of a handkerchief.

The spell plane shift was required in order to create a portable hole.