my guess on the original armour is, that it was sculpted on a bodycast (as was the original elvish armour from the previously posted tutorial) and later moulded in some kind of flexible Polyurethane Foam (at least as a stunt version) or resin or fibreglass ('hero' costume).
To achive a realistic metal-finish, I found that the surface-structure is WAY more important than the actual paint! No matter what materials you use, if you can't get a really nice and smooth surface, it will probably look like metal (well, blank and shiny matal that ist...dirty is much easier ;-) ).
The easiest way for a metal-paintjob, that I usually use on rigid surfaces, is (assumed you have the surface-structure already done) :
- paint all surfaces with simple spray-paint (automotive, 1 component 'stainless steel' or 'aluminium'...) or metallic acrylic paint (multiple, thin layers until full coverage without visible brushstrokes)
- let completely dry
- in small sections: cover completely with black acrylic paint (thin down a bit with water depending on the grade of 'used-look' you want: more water -> less used) and imediately wipe off with a paper towel or cloth until the 'metal' looks a bit darker. Try to wipe in irregular movements so you don't get a structured pattern.
repeat last step as much als you like, even varying the color (browns, greens, dark reds, ...).
For making foam armour I'd recommend this tutorial from WM Armory:
WM Armory Foam Fabrication Tutorial Video - YouTube
The 'black base with matallic paint' - technique ist also a valid option (Look for 'alclad2') but I haven't tested it myself yet. I've heard that it might not be very wear resistant... but if you cover it with clear coat it might work...??
I know from watching many 'behind the scenes' documentaries, that there are ways to get even quite flexible materials to look like metal, or even chrome without cracking the paint (stunt-lightsabers for example) but it took those guys also a lot of time and effort to get there! (the ironman-suit is also NOT aluminium but fibreglass an polyurethane ;-) and many parts are flexible to avoid injuries)
If anyone knows how exactly HOW they did it and what materials they used: I'd really like to know ;-)
