A number of years ago I created wearable costume 'armor' from various themes/sci-fi series that I wore at science fiction conventions. I used discarded 55-gallon plastic HDPE chemical barrels for my source material.
A typical costume would require two complete barrels (much of each was unused flashing material.) One of the more complex costume armor I made was two Serpent Guard/Jaffa Warrior armor, based upon the nemesis characters in "Stargate: SG-1."
Its been a few years since I last had occasion to wear this armor, but I still have it in the basement...
Here is an image of this armor. The head-piece is held to the body carapace with locking hasp clamps on each side of the neck and is removable by the wearer while the costume is being worn.
I had installed a small 9V battery operated computer cooling fan inside to keep the air moving, which would run at top speed for 8 or 9 hours on a fresh battery and this provide excellent ventilation.
Surprisingly, this armor isn't that heavy and it is really quite comfortable to wear...