This is a cheap magnetic chalk board from an online vendor. I had to make the frame a bit thicker with 20x20mm wood blocks to fit the electronics.

A Raspberry Pi 400 with a USB3 SSD is glued with double sided tape to the back. I installed the standard Raspian and added IOBroker to it ( 

In IOBroker I installed the adapters for my home automation appliances (Sonos, Sonoff + Shelly power plugs, Harmony remote, etc.) - there's an adapter for almost anything that has a WiFi connection.

I also added Node-Red ( as an IOBroker plugin with the Raspberry-GPIO nodes.

The switches, meters and the rotary dial are gathered from eBay, friends & family, etc. 

The switches are connected to GND and a GPIO with pull-up enabled. The ampere meters are also connected to GND and a GPIO with a resistor in line and PWM output enabled in Node-Red.

The rotary dial is also jus two switches, one goes low when a number is dialled and the other one is putting out a number of pulses according to the dialled number. It can be read in Node-Red with a few lines of Javascript.