I found this picture of my great uncle, and I can't find a uniform that matches his, particularly the large symbol on his cap.
Any info would be greatly appreciated.
Which cap device?
The crown device looks to be an eagle over swastika. The band device has the letters H, C or G, and W on it. Probably the nationalized manufacturing/industrial conglomerate HGW.
Reichswerke Hermann Göring and Hermann Göring Werke both seem to be names that have been used for it.