This is a small device created to solve the “ultimate household dilemma”—the toilet traffic light.

By displaying a simple red-and-green status indicator, it lets you determine whether it’s “safe to enter” before you even reach the bathroom door. A red light means the toilet is in use, while a green light indicates it’s available—no more awkward knocking, probing, or guessing.

The design features a straightforward, dual-zone indicator layout, paired with high-contrast red and green lights and intuitive human icons, making the information instantly readable—even from a distance—so users can quickly assess the situation.

This creation is not only a practical little gadget but also carries a touch of humor: it takes a subtle yet common everyday scenario and presents it in an “overly formal” way, prompting a knowing smile.

With its simple structure, it’s easy to print and assemble, making it ideal for homes, shared living spaces, or any setting where “avoiding embarrassment” is key.

When printing, please pay attention to the color options—I’ve already noted the colors on the file name, so you can choose either a version with text or one without.

Next, let’s walk through the assembly process:

1. Install the outer casing

2. Install the switch and perform the soldering (with plans to upgrade to a motion-sensing system in the future, eliminating the need for a separate switch). The switch model is SS12D10G5, a three-position, two-speed toggle switch.

3. Assemble the LED strip—the strip is a standard 5V LED light strip, and I’ve chosen a red-and-green color scheme for reference.

4. Solder the charging module and battery—the battery is a standard 18650 cell, and the charger is a typical lithium-battery charging module.

6. Test the lighting

7. Install the back panel, securing it with four M2.5×6 screws.

8. Attach the front panel using snap-fit connectors; simply affix it to the door with foam adhesive or double-sided tape.

Final results:

From now on, you’ll never have to worry about someone barging into the bathroom again!