This is a fully printable, full size Iron Man Mark 42 helmet!
You can read my many updates down below on how I got to this point.
Print out the parts, orient them as you wish, paint them and wear it!
The photos I posted are of a scaled down print, about 50% size. Look at the Makes for what a full size looks like! Please post pictures if you make it! I really would like to see how they turn out, thanks.
UPDATES on how I did this:
Part of the chin piece, the cheek area I guess, was too thin, at full size only one line thick (with a .4mm nozzle). I thickened it using the "make solid" tool in Meshmixer and cleaned it up with 3D builder. I printed it at 30% scale and it came out pretty good. I will post pictures if I print it full size.
Update: added my repairs for the other files. You may notice some look smoother than they were before, Meshmixer does this and I could not revert it but in print previews it looks fine.
Update: I just printed the chin piece, it printed very well but does not appear large enough to be worn. Keep in mind that you will have to scale this to fit your head. My guess is 150%.
Update: I printed the faceplate piece as well at this size. It is indeed too small to wear. Also I will probably update the chin piece with one that is less low-poly, it looks odd when printed. If you have a good way to measure this and estimate a scale that would make it full size please comment.
Update: Added a higher-poly chin piece. - It has several issues, printing not recommended
Update: Replaced the higher-poly chin with a much better more-poly-smooth version. There are still small holes by the cheek area I am working on.
Update: New version of chin-high-poly-smooth. This is probably as good as I will get it.
Update: Added a smoother version of Bo13on's hollow remix.
Update: Added pictures and video of a 50% scale full print. Video here: https://goo.gl/photos/pN9vGhxjybhhzgdY7
Update: Replaced files with 130% scaled ones. It is now full size.
Print at 100% for a full size helmet. Print a 50% for a nice desk model. Use supports when needed.