I found blistree's pattern for a nursing cover and made one of my own. I did a few things different on mine that I wish I hadn't! For instance I made mine reversible but I think it's too heavy that way,and more $ and the boning only likes to stick out one way. Also, I would look harder for the correct size corset boning - Blisstree recommends 1/4" and I could only find 1/2" so maybe (???) that's why mine is weighed down and falls, lying on my chest instead of sticking out - totally defeating the purpose! Moral of the story: Just do what the directions call for :)
~Star
Edited to add: I think I found out the real reason my boning kept falling - not because of the weight of the fabric or the actual boning itself like I thought, but because when adding the straps, both edges of the boning need to be placed directly at the center of the straps... check out my more recent one (and use it instead) here