On level 4, go to the room left from the very top-right room (The one with the large square in it). After finishing this level and going back in, you can place your Mimic where the switch has two trapdoors either side of it near the bottom. If you flip this switch and go left over the trapdoor, you can use the switches to maneuver yourself and the Mimic until you are in the large chamber at the left of the room. Around the center on the left, there should be a broken wall that leads to a room which can take you to level 1, 6, or 7 depending on which doors are open. There are two large numbers in the room, and if you flip the switches so that it displays "07", it will take you to level 7. There is also one somewhere on level 12.