Pre-printed paper locks are the ideal solution if you frequently want to lock yourself out from your phone, computer, or account, while still having a physical paper backup of the code or password.
How to use the print locks
Print out some paper locks and carry them with you
Scan the QR code from the paper lock from within this website and follow link
Change your phone unlock code or the account password to the one on the paper stub
Keep the right side with the unlock code at a safe backup place (i.e. car, work, friend) or simply out of immediate reach
Keep the left side of the paper stub with you to access your lock after expiry (or wait for the open notification)