If you're like me, you're usually really amazed by the amazing cosplays that people create.
One of my first questions whenever I see a costume, especially one with a lot of armor or pieces that would have to be hand-made, my first question is: what is it made of? Obviously there are a lot of options out there for creating realistic-looking armor. I'm going to look at three different building materials that friends of mine have used. Feel free to chime in if you have experience with something different!
This stuff is great. It's not super heavy. It comes in sheets, and becomes flexible when it's heated. AND it sticks to itself, so you don't have to use any glue or tape or anything else that's likely to fall apart after a few hours at a con.
It is a little limited. There's a criss-cross support system built into the sheets, so it can't be formed into really smooth shapes easily. It's better for creating connected panels.
This stuff is really lightweight, so if you're worried that your costume will be an endurance test, you might want to use this. You can paint it to look very realistic, and you can get some really great shapes from it.
Unlike the Wonderflex, it's harder to fuse these pieces together.
Fiberglass is fairly inexpensive, and it can be molded into a variety of shapes. You can read a little more about it here.
It is a little labor-intensive, and it can be difficult to get a smooth finish from fiberglass resin. It can be sanded, but that's another extra step.