If you have seen the Bebe Au Lait covers, those are the inspiration behind mine. I just made my straps Velcro-on instead of using D-rings, which I can't stand.
I also had a face towel that was ruined by bleach stains that I repurposed by sewing them as pockets on the inside, to clean up the baby's spit-up, vomit, poop, pee, whatever liquid projectile that comes out while I'm nursing. Oh, the obvious: milk!
Just used fabric, boning, and Velcro. Pretty pleased with my first nursing cover. Blogs that inspired this were:
Fabric,towel, and boning
The after: nursing cover!
Proud mama-to-be: Saved $25!
The other side: towel corners for spit up