As my first Arduino project I chose to develop an Arduino Mega 2560 controlled layout mimic panel for my H0e “Die Keinnamebahn” exhibition layout. It just requires being connected to the DCC signals sent to the layout and is powered by either a USB connection to a computer or power source or to a 12 vDC supply. The unit, as currently programmed, will mimic the state of up to 20 turnouts or DCC accessory outputs.
This is how it looks, with an Android phone below it used to wirelessly control the layout via a Raspberry Pi 3B+ microcomputer running JMRI. Total cost, including the 2” deep picture frame, A4 black Perspex panel, Arduino Mega 2560, prototyping board, connectors and LEDs was approximately 50 pounds. I shall be publishing an article on its construction and programming in The 009 News, the journal of the 009 Society.