Helmet, dimensions: (assembled) 90.64 x 105.63 x 90.75mm or 3.57 x 4.16 x 3.57in
Please note, the provided model view ports in the helmet do not have the lenses. I only put them in there for rendering reference images. This was designed to go into a fish tank, if you need the lenses simply cut them out of some thin clear plastic like a paper protector, file sleeve or similar.
Do not scale the file down, up is fine. The retainer for the viewport lense is thin but prints fine in resin. For FFF/FDM increase size 25%
If you need any help or have questions let me know.