At the beginning of the pandemic I saw some great printable face shields created to help protect COVID-19 medical workers. Right away, I noticed that many required multiple steps and tools to assemble. I wanted to design a visor with the following benefits over what is currently able to be 3D printed:

Minimal assembly time and no additional tools for assembly
Adjustable shield height
Ability to cover the side of the face, extending just short of the ears
Comfortable during heavy use
Minimal geometry that is easy to sterilize 

The shield uses tension to keep the transparent sheet in place, so all you need to do is slide the sheet in the center opening and insert the shim. Rubber/elastic bands are the only other thing you need.

From March to May, while hospitals were still short of PPE, I printed and fully assembled around 300 shields myself and donated them to Swedish Hospital in Seattle and The Navajo Nation in Arizona. I open-sourced and uploaded the designs to several 3D printing resources (below). Throughout the process I updated the design to help improve print times and comfort. In the early stages of the pandemic my designs were downloaded thousands of times and printed around the world.