EVA Foam Armour Help?

So I'm new to props and replica creation and decided to start by taking items that I had and changing them to fit in the universe of a tabletop RPG that I'm working on.
I've drawn up some early designs for armour and a few shields but I don't know how to actually do it all.

I found a video that touched on a few steps but was so vague about them, not to mention skipping everything up to already having cut the foam to shape, that I'm super confused and more than a little overwhelmed.

I guess the first place to start would be cutting poster board into the templates for the armour pieces? But how would I go about cutting them to fit my body type?

 

There are so many YouTube videos on this and so many other resources that can be found online by using a simple search engine, but yes, creating templates can be a good place to start. Make sure your blade is always razor sharp!

 

Measure sizes of each bodypart (length/width/depth) and write it down.Rescale everything you open in Pepakura to fit your measurements.