I think a cool theme for a pinball machine would be the old n64's but instead of the black ones the colored clear(ish) ones. I personally have a green one still from when i was but a wee lad. Maybe have it the frame made of something translucent with some kind of color tint . Would like to see the circuit boards and wires etc through the back. Have some of the sounds or music from classic games and base some of the modes off n64 game levels. maybe even use some old n64 hardware if possible. It would even look coll as a mini pinball machine