This is the Internet. It might look like an ordinary, perfect rectangular black box with a small blinking light on it, but don't be fooled. This box contains the sum of all human knowledge. Email, shopping, banking, videos of cats playing the piano - all of this. Few people have ever seen it with their own eyes. In fact, the highest-ranking government officials lent it to us only because they believed we wouldn't, you know,I dropped itif youIt's trueIf it were to fall, it would cause a large-scale panic. Society might collapse as a result. But apart from that, it's very safe. It's very reliable. And it's completely wireless.

This Internet appeared in the fourth episode of the third season of the TV drama "The IT Crowd":

This prop is basically a simple black box with a red flashing LED on it. Using a microcontroller for such a simple task seems redundant, so I opted for a NE555 timer flashing circuit:

The blinking speed of this circuit can be modified by changing the resistance value of R1. You can freely use different components, and this website can calculate the behavior of your circuit:Link

The battery is fixed with a rubber band.

You can feel free to use different methods. If you want to replace the PCB board, here are some measurement data.

I used the following parts: