So you have an FX, MR CE, AP, or TE helmet that you bought here on eBay and after looking at it, you've decided that you want to change out the lenses so you can see better out of the helmet? It's really quite quick and easy to do and you have a lot of options here on eBay. You can buy cheap and flimsy welder's lens material that you can cut with sissors or you can opt for thicker true lenses made from colored acrylic. This guide will cover acrylic lens installation, because acrylic lenses will last much longer and won't scratch as easy in the long run. In Star Wars Episode IV - A New Hope, only Han Solo and Luke Skywalker's Stormtrooper costumes had "hero lenses", i.e. "bubble lenses". These bubble lenses typically come with the FX armor kit and are inaccurate. As you probably don't want to be a Rebel and would prefer to go Imperial, you can easily swap these out with flat colored stunt lenses. They come in two colors, Emerald Green or Smoke, and you can buy them in kit form (which can require a belt sander or grinder and a heatgun for forming them to your helmet) or just buy them pre-formed and simply hotglue them into your helmet. If you bought an untrimmed lens kit (that allows you to make either bigger FX or smaller AP/TE lenses), put on a pair of safety glasses, keep the paper backing on the lens material and cut with a table scroll saw (using a very fine toothed blade) or grind them down to the correct size with a belt/disc sander or grinder following the template lines drawn on the material. You can also use a Dremel with a metal diamond-tipped cutoff blade, but be very careful not to let the disc slip and mark up your material. If you weren't given a template, take a piece of 3"x5" card placed inside the eye sockets of the helmet and draw your own from the outside of the helmet following the contour of the eye sockets, then cut this out with a pair of sissors and use it as a rough template and draw a line on the lenses as a cutting template. Remember to leave at least an extra 1/4" all around the template so you leave a small edge to glue the lens into the helmet with ease. Now that you have the lenses cut and shaped to size, you'll have to heat-form them into your helmet so the lenses follow the natural curve of the eye sockets. For this, you'll need a set of gloves and a heatgun. Allow the heatgun to heat up for one minute. With the paper backing still on the acrylic lens, evenly heat them up with a heatgun on high for 23-27 seconds (on 1/8" lenses, less time with thinner lens material) until they are barely flexible, then fit the lens into position inside the helmet and press slightly until the lens bends to fit the contour of the eye socket. If the lens won't bend, heat them up again with the heatgun for a few more seconds and try again. Don't overheat the material or you can cause warping of the lens, making them harder to see out of. Always underheat vs overheat and you'll be fine. Remove the lens and allow to cool leaving the curve intact, then peel the protective backing paper off. The last step is gluing the lenses into your helmet. I'd suggest using a gluestick gun (with high temp gluesticks) vs epoxy or other permanent methods so you can remove/replace the lenses at a later point if needed. Allow the gluegun with gluestick to heat up for at least 2-3 minutes, then draw a small bead of glue around the inside of the helmet's eye socket, then place the lens into place and allow to cool. Alternatively, you can place a small bead of glue on the edge of the outside of the lens (which is why you left yourself a 1/4" extra on the outside of the cut lens), then manipulate it into the helmet eye socket without smearing the glue on the lens. Again, allow to cool. The next step is to draw a bead of glue around the entire edge of the lens so it drips onto the inside of your helmet (keeping the lens in place). Do this slowly and ensure contact with both the edge of the lens and the inside of the helmet at all times. Once you're done with one side, move to the other. Now let it cool down. You now have your lenses installed in your helmet! Clean up any excess glue drips you might have, scraping gently with your fingernail and now you have a Star Wars Stormtrooper helmet with accurate lenses!