We already know that it's possible to map your home's WiFi signal in 2D, but that doesn't help if you're holding your phone above your head to get connected. Step forward YouTuber CNLohr, who appears to have developed a reasonably low-tech way to analyze the WiFi strength of any 3D space. Using just a WiFi module and a CNC mill, he was able to detect the variability of the signal in an area and then create the funky visualization you see before you.
In essence, the system is akin to WiFi radar, using a battery-powered ESP8266 chip to ping a device and measure the signal. If you attach an LED to the handheld hardware, it'll change color depending on the relative quality in a given location. If you've been struggling with a signal blackspot in your home for a while, you can watch the clip below to find out how to build your own.