Finally you can do something with that old LCD monitor you have in the garage. You can turn it into a privacy monitor! It looks all white to everybody except you, because you are wearing "magic" glasses! All you really have tohave is a pair of old glasses, x-acto knife or a box cutter and some solvent (paint thinner)
Here is what I used: an LCD monitor of course single use 3D glasses from the movie theater (old sunglasses are just fine) paint thinner (or some other solvent such as toluene, turpentine, acetone, methyl acetate, ethyl acetate etc) box cutter (and CNC laser cutter :) but that you don't really need, I'm sure x-acto knife and a steady hand would do just fine) screwdriver or a drill paper towels superglue
Most LCD monitors have two films on the glass - a polarized one to filter out the light you are not supposed to see, and a frosted anti-glare film. The anti-glare film we don't need, the polarized one we do - it is used for the glasses.
So, grab you cutting tool and cut the films along the edge. Don't be afraid to press, metal wont scratch the glass, unless there is sand or other abrasives on it.
Then, start peeling. Make sure to save the polarized film, also remember the orientation.
After you remove the film, the glue will likely remain stuck to the glass, so here comes the messy part. With some solvent, soften the glue and wipe it off with paper towels. I started with OOPS, but that was not fast enough so I got some paint thinner. I found out that if you cover the screen with paper towels and then soak them in paint thinner you can let it sit longer and dissolve the adhesive without running and evaporating. Scrape off the soft glue with a piece of plastic or wood. Be careful not to get paint thinner on the plastic frame, because it will dissolve it.
After cleaning the adhesive, assemble everything back the way it was. Before even making the glasses, you can test the monitor with the polarized film! Notice how the upper left corner looks clear, because it has the anti-glare film removed. That is the part we are going to use to make the glasses.
If you are going to use a cnc blade or laser cutter, scan and trace the parts. You can find a local vinyl or laser cutting service, or you could send them to an online service like Outfab.com I scanned the frames so I can use them as a reference for the lens orientation. Remember, this is a polarized film so the angle is critical. Back and front also matters. If you don't have access to a cnc cutter or you don't want to wait for an online service, you can probably tape the old lenses on the film and then cut them out with an x-acto knife.