I made this K'nex Safe/Vault some time ago. I most probably will not post an I'ble (~90-99% sure) so if you want to make it then you'll have to work with this. It uses 2 keys and they move back bolts which lock the door in place.
Bio:I make K'nex guns, specializing in semi-automatic, RBG-Slingshot hybrid systems which i use in most of my guns.
Note: I am not responsible in any way for any damage, injury, or death caused by my Ins...read more »