Trying to make Ramiel from Eva but...

Hi guys, sorry its my first post here.
I was never very creative with my bases on previous versions, so i wanted to make something a little nicer this time.

Im making a small Plutonium fuel nuclear power inside this guy, but im struggling to make the central glowing orb in the middle, any ideas?
I made this one using pannels as #E50000 but i kinda dont like it.