Shannon [Umineko no Naku Koro ni] Cosplay Help?

[BEATORiiCHE]

I was planning on cosplaying Shannon from Umineko no Naku Koro ni (see image to the left). I am going to make the outfit from scratch, hopefully in time for next year. However, while brainstorming what exactly this would require, I ran into a bit of a problem.

As you can see, the skirt of her dress is rather poofy. This is easy to achieve with a petticoat; that's no problem. Where the problem occurs is with the rectangular "slit" in the skirt. Is there a way to achieve the same poofiness without a petticoat, or is it possible to cut a petticoat and have it maintain it's poofiness? Any ideas you may have to solve this problem would be great.

Also, if you have a pattern or two to recommend when it comes to the dress in general, feel free to leave a comment! I haven't even started looking for appropriate patterns, so anything is bound to be a big help.

[Asmo Desu]

☆•••••★【At the third twilight, the surviving shall praise my honorable name on high.】★•••••☆

The Endless Witch, Beatrice says:
★「I plan to cosplay Shanon as well.

What you can do is cut the slit from the petticoat. I plan to do that and see how it works. 」★

☆•••••★【At the ninth twilight, the Witch shall be revived and none shall be left alive.】★•••••☆

[Seraphine the Enchanting]

Cutting a slit should work pretty well. You can also build up the inside, around the slit, with some kind of metal wire for added..er..poofiness biggrin though, that may prove to be uncomfortable, but pain is beauty!
Good luck! 3nodding

[Crazyhatforever]

;] You can always cut the slit and if you never plan on using the petticoat for something else, sew the sides to the skirt.

[A Purple Duckie]

You could have a short petticoat, either sewn into the dress or otherwise. This will give it the poof at the top and let the rest hang down

You could make a hoop skirt attached inside the dress to hold out the shape, and have the hoop skirt be missing a slit as well, if it is attached in the skirt then there shouldnt be a problem