You make a box, then you get a knife, photograph the monitor, print it out, and cut off the excess. Now scan it in and import it in gmax.
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Hope that helps.
thats kind of like what ive been doing... ive been making a box then just welding so its flat.
but then there is a poly on both sides, and i think if you make a plane 2 sided, its still one poly, you can just see it on both sides. but i could be wrong.