This design is super simple and is the easiest invisible door that I've ever seen. Unlike designs that use horizontal pistons, the redstone here is completely hidden underground, and the door itself doesn't create an unsightly dip or gap in the wall. Here's what the mechanism looks like: As you can see, the entire 'trick' is just two stacked pistons. But thanks to Steve__OH's clever design, it's extremely compact. In fact, it's only one block wide. Check out this video of it in action…
