Having seen some reports of the Arduboy case above the screen becoming scratched, I decided to try putting a piece of GuardFilm over it. I had some left over that I bought years ago for another device, so I cut it to a size to cover the screen area.
I don’t know if GuardFilm is still available (the date at the bottom of the home page says 2009 and the supported products are all quite old) but a similar product is Zagg InvisibleShield. These aren’t your typical thin “static cling” plastic protectors. They are a fairly thick material with an adhesive backing that holds well to the surface (but is still easily removable if necessary).
After applying the film as directed, the results weren’t perfect, mainly due to my fault. While sliding the film around to position it properly, it tends to “lock” if too much water escapes, so you have to peel it up and start again. I made the mistake of touching the back with my fingers during peeling and installing steps, which I think disturbed the adhesive, resulting in smudges between the film and the case. They generally aren’t too noticeable under most lighting conditions, though. Most of the time, I don’t notice the film’s there at all.
If I hadn’t touched the back with my fingers, I think the results would have been quite good. From experience with a handheld GPS unit, that I originally bought the film for, I can say that it’s very tough and scratch resistant and doesn’t noticeably blur or distort the display.
In the photo below, the edges of the film are just inside the green lines that I drew. The corners of the film are cut rounded. This photo was taken in bright sunlight, where the display itself would be too dim to be viewable, so the smudges look worse than they actually are.
The denser smudge half way down the left edge of the screen is actually the common one resulting from a flaw in the molding process, so if your unit has that, you can use it to judge how things look overall. And again, note that if I hadn’t touched the back, none of the other smudges would exist. (I still have one more piece the same size left, so I might redo it some day.)