Sorry to bump this, but we've put this stuff together for you at Comet Pinball as a kit using our Matrix products (meaning: no soldering required). In our case, we give you a bulb with a connector that goes into your coin door, and that provides power to the bulbs that illuminate the buttons. There is a quick video on our page showing how to install them. It's really easy.

http://www.cometpinball.com/product-p/kit-lit-button.htm

Normally we have RGB color changing as an option, but those have been selling pretty well so we ran out! Expecting to be restocked on those in a few weeks.

This is true. There are two obstacles for us to making 12v kits right now. If there is demand, I'm sure we could figure something out.

Mind sharing what you used? Maybe that's something we can add.