Hmmmm, I know what a clematis is and what they look like. Google the flower, then you can see, too. I would think this one would be pretty easy to hand cut some petals, they are a pretty basic shape. I think I've seen cutters on some of the European sites.
Sorry I can't be more specific.
Jen 
http://www.homeofclematis.net/variety.htm
I hope this helps a little. This website has each variety listed. Just click on the variety and it will pull up a picture. As far as how to make, I'm not too much help. I have just started making gumpaste flowers myself.
Good luck and be sure to post a picture when you get them done.
cutters to make: (3rd and following items on page)
http://www.globalsugarart.com/cat.php?cid=656&s=60
Here is a site with some pictures:
http://www.clematis.com/html-docs/homepage.html
Wow that is a variety...
It does not look to difficult to make..
It thin to get the cutter would be the best start.
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