Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:2361889.

This is the Blood Dragon Helmet from Mass Effect 2. I added some details to the front and a panel in the back that can come off so you can fit your head inside the helmet. I add locations in the helmet where magnets can be place to keep the back panel attached. They will fit D 8mm x H 3mm magnets.

https://www.amazon.com/Deryun-personalized-Multi-Use-Whiteboard-Refrigerators/dp/B01MZ6EJE2/ref=sr_1_5?s=industrial&ie=UTF8&qid=1496367166&sr=1-5&keywords=magnets

This helmet is size for an adult make but check the dimensions in the pdf file. The units are in millimeters.