Dunno if this is useful or not... actually in minecraft is easier to make a hole in the wall to enter somewhere instead to open a door and enter in a 2x1 space...
BUT if u wanna make some heavy protected bunker THIS should have some value!
My suggestion is a heavylooking metal door that are indestructible for other player like personal safe.
It's explosion resistant like reinforced doors.
This door cannot be opened by redstone signal, but emit a redstone signal when opened in the block where is placed.
Obviusly if u break the block under the door, the door will drop, but if u use a reinforced stone, or better a personal safe that is indestructible and inaccessible, the door should keep the entrance secure.
This door can be opened in two ways:
1-On right click on door, a little GUI with the 10 numbers buttons, one ENTER button and a 4 slots display appear... isn't it clear? a combination door. The first 4 long combination insered make the door open, and this combination is unchangeable until the owner (who placed the door) break the door and replace it. After the first opening, anyone must insert the correct code to OPEN the door and anyone can CLOSE the door like a normal wooden door (maybe getting trapped in).
2-U can access the door like a normal wooden door if u have a Magnetic Pass Card. A Magnetic Pass Card is a simple tool that when in hand and right clicked, open a GUI with the space for 5 combinations. If the combination of the door match with one of the 5 combination, the owner of the card can have free access to the door until he have the card into his invenctory. (is raccomanded to make a copy of the card at home to prevent the losing of the codes in the card in case of accidental destrucion of this one).
Crafting recipies:
Security door:
- -
ID
- - -
where are advanced alloy and ID are Iron door
Magnetic Pass Card:
- -
- -
where is redstone and are paper.
I think that this is a good tool to make your bunker even more protected... a reinforced door can do the job for his streght, but place a lever and the security level fly away from the window... in order to made the access at your 2-3 layer of reinforced stone storage room (or really more important nuclear reactor room) ristrictive, this is a good solution i think...
As the new released Adventure mode, this will also help to give some more option to map creators!
Lemme know what u think