Wall display to show if door is locked or opened(unlocked).
When somebody knock the door and you will use remote controler for unlocking the door,
there is usualy no sign that door is already opened. So persons do not know that they can go inside. This display will show them(with OLED display and some LED ring animations - WS2812/Neopixel) that door is unlocked.

You can even make your own remote system inside(this is not the case here, i am using it just as display).

As it is simple project it is driven by Arduino Nano, no need super fast device here.
There is 12V relay inside connected parallel to electronic lock.
If current is interrupted to lock(by pressing remote controller to open), relay will be OFF as well and Arduino knows that lock is opened(relay is connected as simple button to Arduino).

Printer:
Prusa i3 MK3
20 infill
0.2
PLA

Prusa

i3 MK3

No

No

0.2

20%