The Face Shield is the best design I've found, this is the easiest to print and assemble and covers all the bases including closed top.  35 units can be made from one 1kg roll of pla.  32-40 min print time depending on printer.  Can print 2 at a time on 300mm beds.  NO TOOLS or holes punched, this assembles in 15 seconds and easily swap the clear film and uses a standard size 8.5x11 clear film.

Printed in PLA.  Use 8.5x11 inch transparency or 5-7mil binder covers all available on Amazon, Walmart, Office Depot, or just ask a teacher, they will have some.  See my video below for easy assembly and adjustment.  Feel free to share it just don't make to much fun lol.  I'm just trying to help.

Assembly and adjustment video:https://youtu.be/mHc35-nuro0

Printable Instructions:
https://docs.google.com/presentation/d/1k7t3c5iVB8czOETjJBckdMjMNuYY97rHA7rF7egEBzE/edit?usp=sharing

Make sure to do the first layer at 100% not any bigger or it'll be out of spec for the insertion of the film.