Martin Stevenson build this Stargate SG1 Horus Guard using varying thicknesses of foam and without templates---all freehand! He also added a small flashlight to light up the eyes in the helmet. Foam armor is so quick and inexpensive that the only limits are your imagination and fandom!
And the chainmail is a knit sweater! See more in his RPF build thread here: http://bit.ly/1V4Z38v