The guys in the shop here made a mold of a welding helmet so we could build a few custom carbon helmets for fun. Building your own allows you to put any type of viewing window and filters you preferred or wanted by adding a flange to mount that specific manufactures window/lens assy. You can mix and match any manufactures stuff and build exactly what you want - then paint flames and skulls on it ...
We took a helmet and made a mold from that. (The red stuff is a surface coating) Then using the mold we made a couple helmets. Once trimmed and painted – we drilled out the headband attachment holes and added an adjustable headband. Building the window flange right now to attach the auto-darkening assy that just clips into the mount flange once we bond the flange to the helmet.