The Costume Book

Yes, that is what it is called, though the full title is: "The Costume Book, The Non-Professional's Guide To Professional Results", by Mary Burke Morris. I saw the book first over on As the Resin World Turns, a dollie blog on the sidebar here. Lorraine is an adventurous sewer and she found the book useful to make an Irish step-dancer's outfit for her Mirwen; seemingly overnight.:D

The book does show you lots of practical tips on how to adjust pre-existing patterns to make costumes

but it's more of an "idea book" than a step-by-step how to book. That said, it is stuffed with fabulous reference photos. (It also proves to me that I will never, ever make a full-sized tutu. It's like 40 yards of that horrific tulle balled up to make that cute little skirt. Even the author admits it's a lot of work.) More possible was the sailor/pirate's outfit, with optional belaying pin stuffed in the waistband:

Or this lovely Viking lady's outfit:

The publisher is Schiffer Publishing Ltd, and you can get it directly from the publisher's website or like I did from Barnes and Noble.com (I get a discount there).