I looked at the mannequin and that is a lot fo paper. And I wish I had that shape. I have a few more curves, particularly at the mid section level on the front (belly).
If you want something that will work for a mannequin and that isn't too expensive for the quality you get, I recommend a duct tape dummy. You need help to create one as you CANNOT do it by yourself. You can google it as there are a lot of links on making you own. For those who don't even want to google it, here are two links that I like.
http://www.mixedcandy.com/dtd.html (I'm not a fan of furries but the tutorial is good.)
http://www.alleycatscratch.com/lotr/makingem/DuctDummy.htm (Definitely a fan as there are good articles on creating Lord of the Ring costumes.)
And once the dummy is done, you have something to leave the armor on. Unless you really mess it bad.
If you're looking for something to rest your pieces as you work, you could look into airbrush stands or carving stands. A carving stand is fairly easy to do on your own with piping (PVC or otherwise).
For the sculpting vise, you can look
here. The Web site is in French but you can get a good idea of the build by looking at the image.
And the airbrush stand is usually just a 2x4 with an angled piece on top to hold helmets while they are being painted. Looking on the internet for helmet stand, I found one guy who uses yellow traffic cones as a stand.
Let's not forget our own members who use inverted tomato cages as holders while painting. I think it's a great idea.