I'm intending on using the RPIO library to drive the servo from the Pi:

https://pythonhosted.org/RPIO/pwm_py.html

So I need to connect it to the GPIO pins somehow. I struggled a bit to find a breakout board that didn't just connect to a breadboard or a prototyping PCB. What I really wanted was something with screw terminals, which I finally found here:

http://www.sf-innovations.co.uk/custard-pi-1.html

One Custard Pi ordered. (My girlfriend thinks I'm trolling with these names, especially when I commented that probably the Custard Pi won't fit in the Raspberry Pi case)

I also need some cable to run from the gauge to the Pi. Currently, the Pi sits under the desk just below the gauge. It also runs a NAS and OpenVPN along with a few other server related tasks, so moving it into the back of the gauge isn't an option.

The cable needs to look the part too. It's coming out of an antique gauge, so I need something suitably steampunk and interesting.

3 core fabric covered lighting cable should do it:

http://www.ebay.co.uk/itm/271224071005?var=570170742412