I used Krylon sandable primer on my sintra armor first, then wet sanded it
to make it smooth, then used Testors Model Master Metalizer Lacquer in
"stainless steel color". It's a buffable paint that buffs to a nice metalic sheen.
After that I finished up with a small layer of "Rub & Buff" (a Jango costumers
equivalent to liquid GOLD! 
).
Here's what it came out looking like....
I haven't done it yet, but I also plan on
"weathering" the armor (basically giving it that dull, tarnished look) using
some form of touch-up paint...some people like using regular black spraypaint
misted over from about 4+ feet and then wet sanding it...some people like
using brushed on, watered down, acrylic paints. As with any advice given
on THD...the choice is yours.
Good luck!
Malcfett
