Raspberry 3 b and display power proyect

[syberyandog]

Hello! i got myself an raspberry 3 from a relative and i wanted to do some retro proyect with it.
At this moment im gathering parts and still in the line up of the proyect but i need some input on an idea.

I have an old 12 inch display liying around and wanted to integrated to the proyect as a first step. The thing is the display is 12v and it has a board apart for the video input (RCA). For the first thing i would be using the 3,5 jack and adapt it to give video that way and see what can i do for audio with some speakers apart later, but the most important thing is that i want to make some form of powering the raspberry and the display together.
I dont have much knowledge to begin with , but i love to get to it and learn new stuff by just going around and messing around a bit.

Any idea is welcome!

Thank you and sorry for the language if its kinda messy