I used a piece of 22 gage sheet metal and some 16 gage wire to make this. You can by this stuff at any home improvement store. Happy Halloween.
Step 1: Cut the granite
From there I hot glued the stone to rivet. This served as my handle while shaping the stone. First I spun it round and used a diamond wheel for the initial shaping. After that I shaped it by hand against another diamond wheel. I polished up the stone with buffing wheels and buffing compound.
Step 2: Make the bezel
Step 3: Make the cephalothorax
Next I sanded off any oxidation from heating and laid both pieces on a piece of sheet metal. A little flux & solder and it was set. I used the diamond wheel to remove the excess metal around the body.