Surely someone on this the mother of all prop making community forums can share where to get some template for knight armour?
I have used this site to make a suit of armor out of plastic garbage cans. I have also made a few of the helmets using foam. You will just need to modify them for you own use...
Very True, Early plate armor is very simplistic in nature only covering major vital organs. later armors like Italian gothic plate armor is very articulated and moved within itself. Plate was exspensive and people wore hand me downs and feild plate from won battles. some knights even had half armor and depended on a tower sheild to defend their non weapon side. This gave a person considerable advantage where dexterity is concerned.You should also consider what kind of armor you want to make, throughout history knights have worn many different kinds of armor. Going by the fact that you're asking for templates I'm guessing you want to do a suit of plate, if so then I'd research the time period and style of plate you want to duplicate. Not all plate armor was the same, there were many styles and the styles changed considerably throughout time from plate and mail where you have plates over mail to later full suits where the only mail was in the joints.
Once you have chosen the style of armor you want to make I'd recommend, as Cal has, making your own patterns and templates based on research and using paper and poster board wrapped around whoever is going to wear the armor. I'd also sketch out what you want your armor to look like in the end before you even start so that you can pre-cut your template before you start measuring to simplify things a bit so there's a little less cutting.