First you need to buy the infrared LED light because it forms the heart of your device. Without infrared light you will not be able to see in the dark. Small infrared LEDs are widely available and you can get one from your local electronics store or order one online from eBay. You won’t need a large light and one around 1-2 inches should suffice; however, be particular about a convenient on-off switch located on the light for ease of use.
The blue and red gels or optical filters are the second most important components of your night vision device. You have probably seen these filters being used in cheap 3D glasses often given out at cinemas. While you will only need small squares for your purpose, you can get two small sheets of both red and blue filters.
The tube from a toilet paper roll is going to serve as a cheap and convenient scope for your device. If the tube is fairly long, you can cut it in half and use only one piece for your purposes.
Put the red and blue optical filter sheets on a flat surface and place one end of the tube on them. Now use the black marker to trace an outline around the tube’s end to mark it on the sheets.
Now take a paper cutter to cut around the traced line and get circles of the red and blue sheets to go with the toilet paper tube’s opening.
Use a glue gun now to stick the red filter circle onto one end of the tube. Just apply enough glue on the tube’s edges and on the sheet so that they stick but the glue does not spoil the circle’s centre.
Now repeat the same process with the blue filter circle cutout and place it right on top of the red filter circle you attached earlier. Now both the red and blue filters should be security covering the same end of the toilet paper tube.
Take the infrared LED light now and use the glue gun to stick it firmly on top of the toilet paper tube. The light should be closer to the end which is not covered by the red and blue filters and should be facing away from them.
Once the infrared LED has been fixed and has its batteries installed, take your device to a dark area and switch on the light. Now look through the tube from the end where you installed the red and blue filters, which will form the lens. You should be able to see in the dark now!