If you want to create a red lighting effect for a room or a makeshift darkroom, you can use paper as a filter. : Red tissue paper or thin red vellum.
Creating "red lights" with paper is a fun and simple project, usually for a or a darkroom-style "safelight" filter . 1. Basic Paper Traffic Light Red Lights
: Use a bottle cap or glass to trace perfect circles. 2. DIY Red Safelight Filter If you want to create a red lighting