Quantity   Component name
1 × MQTT and Ruby server Could be anything, from a small Raspberry to a huge server rack. The lower ping, the better!
1 × A stable WiFi network throughout the field Anything that allows the ESPs to quickly connect, and stay connected, throughout your entire arena
2 × or more Lasertag PCBs You can find those over on Aisler: https://aisler.net/Xasin/xasworks-lzrtagpcb/mainboard-esp32
2 × or more fancy shells for the PCBs Those could be the 3D printed casings, old airsoft guns, or something made from carton. As long as it glows and looks great!