A case for the esp8266_milight_hub from here: https://github.com/sidoh/esp8266_milight_hub
This project is awesome because it can emulate a number of wifi
...Show more bridges which allows the user to control more than 4 lightbulbs with one device. The parts for it cost maybe 10 euro. A mi light bridge costs 20 euros and can control only 4 bulbs.
The ESP board that fits inside is this one :
https://www.banggood.com/NodeMcu-Lua-WIFI-Internet-Things-Development-Board-Based-ESP8266-CP2102-Wireless-Module-p-1097112.html?rmmds=search
The box and the lid should be held together by press fitting them. Maybe its necessary to adjust the scaling depending on printer settings. On mine they fit together nicely.
The 3rd picture shows how i connected my esp8266 board to the nrf24l01 module and the settings for csn and ce pins that need to be entered on the web interface.