Bolt Lock Locker

There was once an as-seen-on-TV style device that you could slip over a door bolt lock that would hold the deadbolt in place even if someone attempt to open it using a key, pick, or bump tool.

There was also a site called reddit where someone mentioned it could be created easily with a 3D printer.

The rear plate of this device is 2mm thick. That should be thin enough to fit behind any normal bolt however there should be no issues scaling it thinner (for fit) or thicker) For strength.

The 'plug' can be directly attached to the door via screw to give the device something to grab (via the large round handle hole) if your door does not have an extended frame.