http://plussizebras.info/faq.htmlThe first question, right at the top.
Put another way, do you know how to sew? If not, I'm sure you could find someone in your area who is skilled in that craft.
Armed with that info (as well as reading
this and
this you should be able to get things done.
If you do come across any really good bra resources (websites, manufacturers, custom places, etc), I'd be pleased to add those details to my site under the Bras section. Always looking to improve the site.