If you're willing to pay some extra for having it handmade, there are plenty of people who would be ready to make you one.
(And now that you brought it up, you made me semi-seriously consider actually getting one made. I have a bunch of friends and friends of friends who have cosplay as a hobby, so I might be able to get it cheaper than by going through a professional. Hmm... then I'd only need to decide on the equations I wanted on it.)
I have a half-face mask along those lines made for me by an ex-girlfriend. Sadly, she was not a mathematician, so the specific formulae aren't of much interest. Nice to have for the occasional costumed ball, though.
I met a bloke once who had Euclid's proof of Pythagoras' theorem tattooed on his arm, and got into a drunken argument with him about whether or not he should have chosen a more elegant proof.
To all LessWrongers in London/the south of England: On Saturday the 23rd - this Saturday at 2pm - I will be speaking about Friendly AI at the UK transhumanist group, at
Room 416, 4th floor (via main lift), Birkbeck College, Torrington Square, London (Map)
For those who have read most of the material on the web about FAI theory, e.g. the sequences here and the material of Bostrom and Omohundro, you won't hear much new, but you will probably meet a lot of people who could do with some strong rationalists to speak to. For those who haven't read most of the material about Friendly AI, I'll try to make it a superlatively informative talk. The Facebook event has 30 confirmed guests, and the London Futurists' organizer (distinct from UK h+, the hosts), just emailed me and said:
"Looking forward to meeting you and asking you questions on Saturday! I think your going to get quite a few as there is a lot of interest from my group about your presentation - positive and negative. You might get a very skeptical geezer coming along so be prepared for some tough questions from people who know their stuff."
So the event promises to be a fairly large gathering of rationalists, futurists and transhumanists with a high probability of passionate debate about FAI, followed by a trip to the pub for further discussion and drinks.