Magical Monocle & Invisible Screen




Introduction: Magical Monocle & Invisible Screen

About: The things I make are somewhat minimal in complexity, but I still manage to make some pretty rad gadgets.

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!

Step 1: 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?)

Step 2: 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.

Step 3: 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.

Step 4: 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!

Step 5: 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.

Step 6: 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.

Step 7: Re-assemble the Casing (optional)

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

Step 8: 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!



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    50 Discussions

    This is amazing! I love the idea of using this for geocaching, I plan to make this. Very nice

    Who - this could easily become Steampunked! Thanks for the excellent 'ible!

    Very nice and simple. I'll try it on an old phone first, since they're not doing me any good right now.

    This would make a great hidden clue for an "escape room" game scenario.

    Has anyone tried viewing this with polarized sunglasses? It probably wouldn't work as well, but I bet you could get something to show up if you looked at it right.

    I've seen various other privacy monitor type hacks done to full sized computer monitors. I've always wanted to see someone try it with a much smaller screen and here it is. You did a really good job! Now try and do this with an old phone (flip phone or smartphone shouldn't matter).

    I love this. I am going to make a few to morrow . I know all my friends will want one .Thank you so much . Exhalent instructable.

    i want to make it anyway, but can you help me, how to find digital photo holder? couldn't find at Amazon and other. i need it. contact me at

    1 reply

    Try "coby photo viewer keychain". Example:

    can it be used for mobile phones as well ?


    2 years ago

    you could soak the

    polarizing filter

    in oil too for removing the glue

    Hi ¡¡¡Nice gizmo!!!. A tip from Argentina. A very good way to remove adhesive residue is to use isopropyl alcohol. As says makemike wd40 also works, but then you have to wash so that there is an oily layer. Best regards. Calistoar.

    4 replies

    The adhesive used is hardly effected by polar solvents like iso-propyl alcohol without a lot of elbow grease. On the plus side IPA also doesn't effect anything else. You are right about the oily residue with WD40, and in some cases WD40 and other penetrating solvents can penetrate the other layers you want to retain.

    Ligth_lab Hi, ¡¡thanks for the comment!!. I'm a chemist, you are right about that polar solvents not overly affect the adhesive used to attach the polarizer film to the screen , but some time ago, I used IPA to clean the adhesive from film rescued from a broken tablet and it worked great (true, I had to rub a lot!). I think nonpolar solvents such as benzene or toluene dissolve very well the adhesive without affecting very small iodoquinine sulfate crystals embedded in the plastic layer (is the active stuff under by which light is polarized), but, ¡¡¡who wants these carcinogens in the shop (and therefore brain) !!! I send a big hug from Patagonia Argentina.

    I am a chemist too ~40 years polymer chemist, the last few years working with projects involving LCD screen construction. The adhesive does not dissolve in the IPA but the IPA wets the surface and stops the adhesive sticking, so it gradually beads and is removed mechanically or sticks preferentially to the cleaning cloth.

    The liquid crystal material is actually between two sheets of thin glass not plastic. Or at least the dozens I modified were two glass sheets each about 0.5mm to 1mm thick. It is this glass layer that one has to be careful about not cracking. Also the edges of the glass sheets are often razor sharp. The cuts you can get are worse than paper cuts and take ages to heal. The sharpest edges I have found are on Mac LCD displays.

    Hello, Light_Lab. You're right, it is true that the IPA does not really dissolve the adhesive that bonds the polarizing plastic layer to the the glass plates that maintain the structure of liquid crystal and electrodes (aka "glass screen")... Actually would have rather a softening effect.

    And it is also true about the sharp edges of the glass layers, as you say, are more sharper than razors, I have suffered this.!!!. A hug from Patagonia Argentina .

    A few drops of Goo Gone might work two. It's great for any pesky labels or stickers

    This is a delightful fun project for any parent wanting to actually get there children to get up off the sofa or bed to do chores. it's also a fun project for children to do with there mates for instance a secret code club where only the members can read the messeges on the screens.

    1 reply

    The thin glass used in the LCD screens is dangerous enough for adults; I wouldn't let any child under the age of late teenage near it. The cuts are worse than paper cuts and take ages to heal.