How to make an Mark 6 reactor for mounting on a guitar?

I am trying to make my guitar look like the armor of Iron Man. I have seen lots of versions, but the Arc Reactors I have seen are all too thick to mount under the strings on a guitar. I just want to make the triangle that lights up in the center. What materials can I use to make the frame the exact size and height that I need? And what can I use for the top cover? I never made anything like this before. So any help would be appreciated. I included a pic of the guitar. I would like the reactor to cover where the middle pickup used to be. Thanks!