For certain applications a red lensed flashlight can come in very useful. If you are looking at star charts or trying to get around the woods and want to not ruin your night vision, these are perfect.
This instructable makes one from parts you can find very easily and cheaply.
Step 1: Supplies
For this instructable you will need:
1. LED flashlight, the one i used is from a walgreens, you can get these lights for much less on ebay, about 99 cents.
2. Red Photography Gel, This was free from a photo store down the street they give away sample packs to students.