Improving physical security at a hotel

Problem statement

We’re on a family vacation and found ourselves in a hotel… where they don’t pay much attention to physical security.

And since “under door” style attacks are a thing, and the hotel door had a huge gap under the door1… I decided to fix the problem.


This is actually rather straightforward. Let me give you the money shot first:


That’s a result of about 10 minutes of quality time in Fusion 3602:

[Right here should have been an interactive 3D model.]

Followed by about 20 minutes of printing time (at the lowest possible resolution on a Prusa MK2 printer3).

As always, the design as well as the STL file are freely available under CC – BY NC SA license4.

Update 2022-04-30: I spent some quality time with OpenSCAD and came up with a new version:

[Right here should have been an interactive 3D model.]

It should be usable even when there’s just a slim gap between the handle and the door.

The design and stl is released under CC – BY SA license.

Closing words

Surprising no-one, this quickie is not enough to protect against an improved under-door tool.

But I think I have an idea for a simple workaround for that5, too. Just don’t have a pressing need to materialize it. Let me know if you have one of those improved under door tools with a claw… and want to co-op on the workaround.

  1. I guess that was part of their initiative to “soundproof” the rooms? :)

  2. You know the drill – 2d drawing, extrude, chamfer, done.

  3. Thanks to Skurt for letting me use his desktop and Prusa.

  4. The non-commercial bit because I don’t want to get into hot water with Autodesk since my license is the free hobbyist one.

  5. In essence, put a “lid” on the handle that rests on both the “axis” of the handle and the console; fastened by a zip tie around the “axis” (& neodymium magnets on “console”). Not sure how much force can the under door tool inflict, but this could be enough to stop even the claw version.