This handy little tool can be used to check for any Wi-Fi signals around, use it to see how well the connection in your workshop is going or to see if there’s any free Wi-Fi hotspots when you're out and about. Using the beloved 8266 we've attached a screen and let it run off 2 AA batteries. The screen is suited for 5V but it tries (and succeeds) at running at the lower voltage. You could even use rechargeable AA batteries in this one.