Start with the boots, and work up.
Get some brown boots, and some strong-ish cardboard and cut out the tips. Actually, you should ask Nikki what she did for her Kuja boots, because they're very similar.
Shin guards for soccer players would be a great place to start for the leg armor, and look for some gardening gloves for the gloves.
The helmet and chest you are going to want help on, but not from me, from someone who can actually do this stuff. Those will be the hardest 2 things.
You're going to need lots of spray paint.
I wish you luck.