I made the pattern, but I used a sweatshirt hood as a base. Lay it flat on a piece of tissue paper and trace around the edge with a pencil. Just remember to flare out for the shoulder portion: basically, it's the shape of the hood with a wedge extending from the bottom. The bottom edge, the hem that'll rest against your back and shoulders, should be curved. Don't forget to incorporate at least half an inch of margin all around the edge for hems/seams; I'd do more at the front edge so you can do a nice, deep, finished hem (where the raw edge is tucked inside the hem). A deeper hem along the front edge will keep the fabric stiffer and crisper, preventing drooping. You can adjust your pattern as necessary, sketch it larger if the sweatshirt hood will be too small, or deepen it so the front will come down on your forehead more. Practice with some cheap muslin or other scrap fabric until you get a shape that works, then use your good fabric.
The face cover portion was just a rectangle with a band attached to one of the short sides (kind of looks like an apron by itself) that's then safety pinned inside the hood. The band fastens behind my neck and helps keep the cover closer to my mouth and nose. It also helps draw in the sides of the hood somewhat. I like keeping it safety pinned instead of permanantly stitching it in place because it allows you to reposition the cover as necessary. As long as it's pinned from the inside of the hood, it's not really noticeable.
Close-up, even, the pin's not visible at all.
You can kind of see the band
here.
If I could do it in such a short period of time, I'd do Pazu from Laputa or Asbel from Nausicaa. But I've got other commitments that need to be finished first. If they get done and I've got time left, maybe, but I don't see that happening. Besides, I've already got four costumes I'm doing, and my boyfriend's pushing for a fifth. I'll have to put either of the boys, or the completed version of Ashitaka, off until Aki Con. Wasn't even sure I could come to this con until about a month ago, and just found out 2 days ago I can attend the whole weekend. Less prep time than usual.
Could do dark dress version of Sheeta, but once again, the biggest issue is time at the con. I hate changing several times a day, takes up too much of the con.