This small part can be printed alongside the 3DVerkstan Face Shield designed by Erik Cederburg.

https://www.youmagine.com/designs/protective-visor-by-3dverkstan/

It only adds 5 minutes and 3 grams of material to the print. The way it works is that you attach a small strip of 1/2 inch (or 12mm) high density/closed cell foam tape and then press it on to the forehead piece on the frame. If you're wearing these without rubber bands, you probably don't need it. If you're using a rubber band to keep the shield on your head, this may make it more tolerable to wear.

I print everything in PETG because that is what my local healthcare workers told me they were most comfortable with in terms of cleaning and preparing. It's also flexible enough for this to work. PLA or ABS might not bend enough to work for this.

UPDATE: I've added a simple template for a top cover to go above the forehead. This will work with most existing face shield designs that use the same 6-hole pattern based on the north american 3-hole punch. It addresses the number one concern that most people have with these types of frames. I can get clear binding covers for approximately 17 cents each. So this additional piece only adds another 9 cents to my cost. There's a little bit of time spent in converting it but I'm working on making some jigs and assembly instructions to streamline this process.