3 high 3x3 flush piston door v5 (current smallest)

Build image: 
In-game name (NO VISITORS! Must be LEARNER rank or higher!): 
NvrGonnaGiveU_Up
Builder name(s) and current ranks: 
NvrGonnaGiveU_Up, Learner
Creation location: 
715 186 -224
Machine Features: 

3x3 doorway, closing flush with the wall, and all the redstone operating it is 3 high. There are 4 entities in the door that act as long delay timers, and there is one more to limit the delay of one of the timers. Lots of observers and hopper timers, and even a block or 2 in the doorway, which are entirely legal by the "official" rules for redstone doors.

How To Use: 

There is a lever on the left side of the machine, on the side of a note block. Flick that and the door will open/close. wait for the door to stop making noise to power again. There are brief 10s pauses during the operation of the door, so please wait for that too!

P.S. Don't nudge the carts or touch string/pressure plates, thanks!

Request status: 
Approved