... and to add to that: I just got the JoAnn's flyer. June 7-9 all Butterick Patterns are going to be on sale for 1.99 each (And I think the Vogue ones are on sale for something around 3.50 each, too).
The best thing to do if you're "pattern bashing" is to make a copy of the original pattern on either a large piece of paper or some cheap scrap fabric (muslin is common, but hey, if you got a bunch of Aunt Mildred's ugly 60s & 70s flowerprint fabric free, this is a great use for it ) and then tweak from there. I like using the free ugly fabric for testing patterns because it drapes nicer than paper (and doesn't rip!)... plus, you can baste it together and try it on to confirm it'll fit / look right before you start cutting your good / expensive fabric (also note that since it's functioning as a pattern, if you find a piece is too small, you can simply attach a random scrap to the too small section and instantly expand the fabric's size... then once it fits / looks right, you can mark the seamlines with a sharpie pen (and mark locations of cool details on the fabric with the same pen - this way if your costume needs appliques of certain things, you'll be able to test-draw it to confirm that the detail is in the right location. Remember: anime characters are a different proportion than normal humans, so certain details will not be exactly the same shape on a real body as they are on an anime character).
Do bring some of your test patterns and suchlike to the June meeting... I'll be there and can help with figuring out how to tweak 'em. (hmmmm...
sounds like a pattern bashing panel may be called for.)