What you would need to do is make ones that fit you perfectly, then go to the cons and model them, and take orders. Hand make them to fit specific customers.

Yes, I was coming to realize that each one would be a custom job. The inventory required to do any differently would cripple me.

And if you got really good, and really liked it, you could get on the set of plays and/or movies as costume designer when folks did adapted versions of the books. :)

In my dreams! (Costume designers get someone ELSE to do the grunt work.) But that'd be convenient -- keep from having to redo all the designs when the movie comes out. :-)