￼ This dimension has only appeared once. In the episode "The Bewildering Bout of the Astonishing Automotons". In this episode, Penn is nowhere to be found. Only Boone and Sashi. This is because the mission is that Boone needs to build an automoton (Penn in this case),to fight an evil automoton built by Larry who becomes Rippen. If Penn were to lose, the evil automoton would be mass-produced to make an evil army of Automotons to conquer the world.
￼￼This location is mostly in the air, hence why everyone flies in blimps and helicopters. There's even a running gag where Boone and Larry crash their blimp.