Hello everyone,this day a(maybe) good idea for a mod appeared in my mind. The idea consists in a server plugin which gives the player the ability to create: A panel with a 1-9 numpad next to a locked door.You decide which number succession it will be,and it won't open if it is not correct.
An Obsidian-reinforced chest: It will not explode with tnt,and has the same panel as the door: Only unlockable with a certain number succession.
This is just an idea,if you decide to create it don't give me any credit

I'll upload a new image when I finish the texture of the panel.