A few caveats beforehand: While the methods I employ here were able to furnish me with a finished helmet, I am in no way saying these are absolutes! In the end, the best processes to follow are those which you are most comfortable working with, so if there is something here that seems easier to do in your own way, by all means feel free to modify the process to your preferred flavor of building.
I should also note that this is a complicated and lengthy process. The final result took me a little over 4 months to realize, so anyone looking to follow a similar path, be prepared to be in it for the long haul! That said, this is only my second helmet project. If you're more familiar with electronics, casting, moldmaking, or just plain have more freetime than me, your results may vary. This project encompasses elements of sculpting, mold making, casting, soldering, electronic design, and lots of good-old-fashioned sanding.
I am entering this Instructable in the 4th Epilog Challenge because, as you will see, having a laser cutter for some steps in this process would greatly improve the productivity speed! I am an amateur propmaker by trade and, more recently, profession - having a laser cutter to expand the capabilities of my studio would allow for a whole wealth of new opportunities.