Basically this is like my other power station door, but for mountain bases. It uses sticky pistons, but is far more complex. It uses twice the amount of repeaters, and the wiring cannot mainly be on one side, unless you have a lot of height and patience. This took my about 3 hours to work out, but none of the redstone or pistons is visible, and it is still lockable when you are inside (See other door design for details)