I usually avoid props because I don't have much space in my tiny little apartment to work on them and roommates don't take to kindly to syrofoam shavings all over the place.
Still, for Sakuracon last year I went after one of my dream designs, Miku from the art for STOMP THE ENEMY. It was more doable in my space because I used cuts from sheets of plastic to make a geometric, boxy kind of shape, as opposed to anything that would require actual sculpting and sanding and so on. Plus I got to use my Physics 211/212 knowledge to get some lights in it!
I'm really proud of it but it's pretty uncomfortable to wear since it's heavy on my nose and I since it's all enclosed I can't see anything with it on.
Here it is:
And one where you can see the colors a bit better (my lights were too bright for the camera in the dark, apparently)