How would you build the Alien suit?
What would be the goals of the design?
In terms of how I would want the creature to look, under the movie lighting, I would want it to look as much like this as possible:
I would also want it to be comfortable for the body actor, and for the suit to come off and on easily.
My idea is also to make the suit as close to the original Alien, from the first film, but even take it a step closer to Giger's design, by using materials that would allow the actor to look even more thin than any thick rubber suit would allow.
Essentially it is a combination of the methods used by Winston in Aliens, while adding more detail than his suits had, via airbrushing on the neoprene itself. Also it would be worn by a 6'8"+ and very thin actor. Myabe someone with Marfan Syndrome.
Here is what I would do:
