Enjoy this 'lil how to article on how I built these suckers heads.
First up, lube up a non-stick surface w/ some petroleum jelly. In this case, I used this girthy old marker I had lying around. (Note: Gerold pioneered this technique but I believe I'm the first to apply it to warhammer modeling) Roll out some green stuff blobs and smash them down with your well lubricated finger. Try to get them to a uniform thinness if you can. If you slide your finger back and forth real shifty like you can avoid fingerprints.
Let that sucker cure for at least an hour or so and then pop em off. They should be a little bendy yet, but cured enough you don't get a bunch of fingerprints on them while handling. Using a little scissors you nicked from your girlfriend's makeup kit, cut them into triangles. Regular scissors actually work fine as well. I was able to get 3 or 4 out of each of these little pieces, sorta criss-crossing the cuts back and forth so the edge of one triangle became the edge of the next.
Don't worry too hard about trying to make sure they're the same size as once you've cut these buggers out, you'll start matching them up by shape. I always had some leftovers to toss. You could try to trim them down but I found it easier just to whip up another big batch and pick out similarly sized ones. Once you find some roughly the same size, cut an indentation on the short sides.
Now you just need to stick 'em to the head hole. Ring that bowl with some fresh putty and start laying them down, one after the other, covering up the edge of the one before it. Once you get all the way around pull up the edge of the first one and lay it over the last, creating a perfect star sphincter.
Once they're down I mash the whole business down to the underlying putty good with my finger first and then a sculpting tool. This is the only point during the entire process I used a sculpting tool. Once it's mashed in good, you can curl the petals however you see fit. You'll need to way overcurl them to get a slight curl in the end since they're almost cured at this point.
Once they're cured, you can test how well the whole thing is sticking to the head. I had one that was not secure, so I popped the whole thing off and superglued it back on. The rest were solid even though no glue was used.
Not much to be done after that. Just glue a bunch of green stuff tentacles you already rolled up into the head hole and call it good.
This sort of technique can be used for all sorts of green stuff work such as capes, armor plates, and the like. It's always easier to cut out the shape you want than to stick a blob to the fig and try to work that green stuff dookie into something that looks good.
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