Here's Vader with a coat of primer and some lenses.
The lenses were made out of smoked acrylic sheet cut to shape on a bandsaw and then put in the oven. The plastic goes all floppy like leather so you can position the lens and then press it to shape using the back of a tablespoon wrapped in waxed paper. There's very little imagin distortion as a result of this method. The lenses will be glued in once the maske is painted.
I have also cut the slots in the top of the cheeks and reworked the nose. You have to sort of scoop out the sides of the nose so that the eye is more lemon shaped than triangular.
You know you've got the right shape when you fingers can naturally follow the curves when your rubbing the mask down with wet and dry paper.
The mask is now 'pretty much there' and just needs another going over with knifing putty and wet and dry to remove the final small flaws that are still there. I don't want the make the Vader masek too good since the real prop is also not perfect. The flaws add to the character of the piece if used carefully.
The helmet in these photos is the original (but reworked) Rubies one. I have not yet made a cast of the helmet so I can make a thicker GRP one.
The two shots below are different angles of the same sate of play.