I tend to watch DefCon and Pentesting videos on YouTube fairly often. I came across one that was talking about door attacks, and how most modern buildings use lever handles. Given their susceptibility to under/over door attacks, a number of hotels have implemented blockers to prevent the loop from catching. I figure having a design handy to print can make your office/workspace/what have you a little more secure. I've made two versions, one with two sides, one with one side. It should act as a shroud to prevent any door attacks.
The introduction/vulnerability in action: https://youtu.be/rnmcRTnTNC8?t=1008
Here's the reference of how it's meant to be utilized: https://youtu.be/rnmcRTnTNC8?t=1200