I made this Statue of Liberty prop for a Planet of the Apes game in the spring. Kind of narrow, but I think the concepts are sound and can be applied to a wide variety of props.
I started out by making the torso. The cardboard box is there to provide stability and a basic shape. I formed stainless steel mesh I got from Home Depot around it, cut slits in the shoulders, shaped it, and held the whole thing together with floral wire.
Then, I made the rough shapes for the arms and the head. I glued together sheets of styrofoam insulation, also from home depot, and used a saw to cut them into blocks about the size I needed.
I then carved the head and arms out of those blocks of styrofoam. Since the face contains a lot of detail that I didn't want to spend a lot of time on, I spent a couple bucks to get a cheap mask from a party store. The arms are supported with a combination of floral wire, and pegs made from wire coat hangers.
Here you can see I've added the second arm. I've also added some details, like the crown, which was cut from cardboard. I also added the hand, which I made by making a skeleton out of wire coat hangers, fleshing it out with fabric and tape, and covering it in an old glove. The torch is made from a flashlight and a cut up deli container. One less obvious thing I've done is coat all the exposed styrofoam with Plaster of Paris, which I've done for 2 reasons. One is to give the skin a smoother texture, since you can't smooth out styrofoam completely. Also, I did it to protect the styrofoam from the upcoming spray paint, since, in case you didn't know, styrofoam melts if you spray paint it.
Sanded down the plaster to get rid of some of the super rough spots, and gave it a paint job. Also added a torch flame, made from a piece of wrapping paper/toilet paper roll.
Then made the robe out of a bed sheet.
And after all the time I put into my relationship with Lady Liberty, she wound up going home with some other guy after the game. I texted her once or twice since then, but never got more than a two word response. I hear their relationship is getting kind of rocky, though, maybe I'll have another chance with her down the road a bit.