This is the Senate Guard Helmet from Revenge of the Sith.
I hope I'm getting better at sizing these helmets. This "should" fit an adult male head. Please check the pdf for measurements. The units are in millimeters. If you do print this out before me please let me know what scale fit your head.
I design props and costumes mostly. I am not an engineer nor a trained artist. I learned almost everything from watching Youtube videos and just messing around in designing software. I started designing with Fusion 360 in August 2016.