“Under-door” style attacks are when an attacker slides a tool through a gap in the bottom of a door, hooks the inner handle from the bottom, and opens the door by pulling the handle down. This type of attack usually works on doors and locks found in hotels where the door is left open by turning the handle from the inside. [Michal Jirků] Found himself in a hotel room with a particularly large gap under the door and decided to quickly design and print a door guard to protect against such attacks.
It is a common object, and it takes twenty minutes of printing and a little double-sided tape to set it up. Since an attacker attacks an under-door with a major mechanical difficulty, it doesn’t take much to frustrate the effort and the object does just that. Physical safety is especially important in hotels, above all, and miscreants are known to exploit known flaws such as face-pamingly bad onity key card lock exploitation.
If you have trouble illustrating how this works, this video demonstrates an under-door action, so you can see how the tool that blocks space by the handle will easily prevent the tool from going where it needs to go.