Hi TKey, welcome to the 405th!
I guess the first question is: what material do you want it made out of?
If you have access to a 3D printer, you can 3D the parts. The pieces are solid and feel more like real armour, but are also heavier, need padding and well... access to a 3D printer.
Foam is a great beginners method, being lightweight and the materials and tools are much more accessible to everyone.
Pepakura (Papercraft) is not as common nowadays, but still a valid method. You make the armour out of paper/cardstock, harden it with resin and then built it up/smooth it out with body filler.