Thanks again! I think I've decided to scale down because in the off-chance I can manage it, I was thinking of doing exactly what you suggested and finding some way to build a harnass that would keep the Koffing "floating" over my shoulder. That's phase 2 though and I figure I'll cross that road when I get there.
I've tried to do some research, looking at your advice and looking at how other people make props because this is literally the first time I'll be making anything and I know nada about this world of creating. Basically, I'm a super newb. Does this sound like a sound strategy?
1. Rather than create a foam ball, I was going to purchase an orb from this site. http://www.shapeinnovation.com/products
They only have 13'' 1/2 lb EPS spheres, or I can go with a 12'' 1 lb EPS sphere. I'm not sure if the 1/2 pound of weight would be that much of a difference, so considering just going with the 1 lb sphere.
2. Elevate the foam sphere by placing some kind of needle in the bottom and coat it in a fiberglass resin. Let it dry. Question about this -- I have never worked with resin before. Is it going to be black? If so, to get the color of the Koffing, should I apply a white paint afterwards first or do you think painting on top of the dark color will still get the color I'm looking to achieve?
3. To achieve the volcano-like protrusions, I was going to cut plastic cups in half and gorilla glue them to the surface. I was then going to use model magic to surround the cups, and "dip" into the opening at the top to create that crater effect. The cup would be just to aid in giving the shape, making them more uniform, and providing some sort of infrastructure.
4. Paint the sphere using purple, black, and maybe a darker purple to use for highlights to create depth in some area. Would spray paint be the best method? I've read about several different kinds of paints and I'm still confused as to what's best.
4. I am going to be making a more menacing Koffing, somewhat based upon this image: http://www.wallpaperup.com/uploads/w...4e88a72766.jpg
So I'm thinking about using the model magic to form the brow ridges and lips/teeth. Wait for it to harden, then handpaint the pieces using the same paint for the rest of the Koffing (whichever type you suggested I use).
I've sketched it all out and did some scaling of dimensions. Next step will be the actual building if these steps sound right to you.