This glitch involves mapmaker, so fire that up and make a new map, and make sure the tile set is Industrial. Put down adapter 3 (crab ramp), and the put a large pit next to it, (So the bottom of the ramp is next to the top of the large pit.) Go halfway up the crab ramp and face the large pit wall. You can do this either side. Run straight into it, and you will fall through the wall and see only pitch black, you will also die. So, put down a small room, like a double corridor. Once you do that you will be able to stand in the pitch black, because technically, you are in the double corridor.