Magical Monocle & Invisible Screen

A physical key (or monocle) to the digital world.
This could be useful for stages in geocaching, high tech treasure hunts, or even making your children clean their rooms until they find the monocle-key. (The device could hold a image of the WiFi password of the day.) If any other clever applications are thought of, tell us about it in the comment section!

Updated 6/12/2021: If you would like to order one of these small displays with all the hard work done (separating the polarizing filter from the screen) already completed and ready to go, please direct message me. It would have the rechargeable battery removed for safe shipping. I am selling the device from this project.

Parts Needed:

1. Scissors
2. Keychain ring
3. Micro screwdriver set (Can be found at many Dollar Tree stores.)
4. Hobby knife (The knife I used had a cutting blade on the tip, not the side.)
5. Digital photo holder (I used a keychain version.) ($3 to $13 US dollars on Amazon.)
6. (Optional) Small container filled with warm water & soap (or possibly WD-40?)

Remove the Electronic Photo Holder's Casing

Using a small philips screwdriver, unscrew the main casing screws. Then, carefully pry open the casing with a flathead screwdriver. This should make the LCD screen accessible.

Remove the Polarizing Filter

Basically, you are trying to scrape off the very top layer of plastic sheeting on the LCD screen, which should be a polarizing filter. With your hobby knife, start to peel off the top of the plastic sheet at the corner, and then peel in rows until the polarizing filter is removed. Think of it as shoveling snow, if you want. Be careful not to scratch the LCD screen itself, or damage the polarizing filter.

Clean Glue Residue Off of Polarizing Filter

With warm, soapy water, soak the polarizing filter only (the tinted plastic sheet you just removed) for a few minutes. Then, rub the filter between your fingers until you have removed most of the glue residue.
Side note: If anyone has a better technique to remove glue residue, please tell us via the comment section!
Side note: A commenter said to WD-40 spray on the polarizing filter, let it sit a few minutes, and simply wipe off the glue residue! I haven't personally tried that technique, so attempt at your own risk!

Find the Optimal Polarizing Filter Orientation

Note how the angle which you set the filter effects how the image turns out. (Don't forget to charge up the electronic photo holder!) Also, with some photo holders & sunglasses you can kinda see the image displayed even without the filter. However, with most LCD's you can barely tell, if at all.

Cut the Polarizing Filter to Fit Into the Keyring

Once you have cut the filter to size, slide it in between the parts of the keyring.

Re-assemble the Casing (optional)

With the screwdrivers, screws, and casing from earlier, place the electronics safely back inside the original plastic casing.

All Done!

Project complete. Load your photos into the photo viewer like you normally would! I am a sort of compiler of ideas and concepts I come across, so if you're wondering how I came up with this project, I had read that sometimes in the army, the polarizing filter of the computer screens in (rec rooms?) are removed and glued to old sunglasses, so as the prevent pesky screen-watching.
I hope you found this instructable fun, or at least practical!