My Garen Cosplay

Im making a garen cosplay for a convention in june and this is my first time im making a costume, i have plans for most items but i need a little help

Shoulders and gauntlets - im gonna use a floor mat foam trick that i found from a guy called evil ted on YT

Sword - im gonna use a video as a basic idea to make it https://www.youtube.com/watch?v=gcDCZ2TmTck

chest piece - this is what im having a little trouble on, i was thinking of using foam for this but i need a little help

Any other suggestions would be appreciated