hmm thats an interesting concept but it wouldnt look like the prop is supposed to look, it would help me see but im fine walking around with half vision
unfortunately right now i am out of the country and cant post measurements sorry
but it should be easy to figure out, just take out a ruler and hold it up to your face while looking in the mirror and that should give you a good idea about the length it should be, from there i just did it by eye myself and it turned out well
As for instructions i did list how i made it at the beginning and its easy to see actually that its just made of about 3 layers of different thickness styrene, I just then sanded it to the angled i wanted on it and used body filler to fill in holes in the styrene's surface, If you did it yourself id suggest wood as it would make it easier to get a nice finish
beware though while it is quite a small prop and initial build time isnt long (about 2 hours to get all the main shapes in place) its filling in holes with styrene that took me ages