ABS at 0.2mm, 10% infill.
Printed directly as scaled originally. Was slightly too narrow for my head, which is 175mm just in front of my ears, but I modified it after printing to fit.
The headstrap I used is a knock-off ebay special GoPro head mount. The straps superglue to ABS amazingly well, and it's relatively comfortable to wear. Also added a foam pad to the nose bridge