Frame built for balancing robot.  I used a 3mm acrylic sheet built in 3 tiers using stand offs.  Motors, battery holder and electronic module boards are also fitted. The modules are a MPU6050 which is a  3-axis gyroscope and a 3-axis accelerometer combined, a L298N a dual H-bridge motor controller. Currently I have both an Arduino Nano and a ESP8266 onboard.  The initial thought was to use the ESP alone but it looks like it wont have enough GPIOs (at least not without a lot of jumping through hoops). So currently going to use the Nano to control the robot and the ESP to communicate with it at least that’s the plan.  However I am waiting on a couple of ESP32s coming from China these have built in Bluetooth. There is also the option of adding Bluetooth to the Nano.  Watch this space.