Just a quick update, as I haven't posted anything in a while.

The project is still very much on, but it is hinging on a pcb design. Luckily I am getting some help with that, and in the future we should have a great board to connect the Pi Zero, arduino nano and the ESP8266 together, with plenty of io ports on the board for connecting relay boards, sensors modules etc in a very modular way. There will also be extra i2c ports for daisychaining units together.

Until the board is ready I am keen to make a new prototype to allow me to keep refining code. For ease I would love to be able to use as many off the shelf component as possible to make prototyping easier; that's where @Hartmut Wendt and his awesome Arduibox comes in!

Hartmut has a range of amazing DIN rail enclosures for Raspberry Pi and Arduino available on his webshop. I was lucky enough to get sent a prototype for his Pi zero-based one, and have running a demo webserver on it ever since.

I have just ordered Hartmut's Arduino box enclosure; it takes an Arduino Zero and a shield, while still leaving space for prototyping and extra components.

I have also ordered a relay shield for arduino, and an extra lcd shield too.

I'm going to experiment with using the lcd shield in the case and trying to fit a 4 channel relay module in the case too.

If that doesn't work I will switch to using the relay shield and an alternative screen. Hartmut has just released a fantastic i2c OLED module board that can be added to any of his enclosures, so I will look to order one of those and explore how to use it using a software i2c on the arduino (keeping the main i2c bus free for just master and slave unit addresses).

Cheers!