Relia-robot

You built a door into a crack in a concrete wall, and found a concrete valley beyond it; a transparent river flowed through the center, and you spent years carefully bringing dirt and plants through into the pocket reality you'd caused to manifest, and then insects, to sustain the plants, and so on until it was impossible to tell that concrete lay beneath the verdant surface, grey and unchanging. Eventually you built a cottage from the wood of trees you'd planted, and found less and less need to leave your pocket world to the larger outside.