A friend of mine is having her 5th baby in a few days and never had a nursing cover. I couldn't let the misfortune to go on any longer!
I think having the double layers helps the peep hole stay open while nursing. I also like having pockets on the inside to store pacifiers, nursing pads or burp cloths.Made by the Mamamonster has a great tutorial that I follow every time I make a nursing cover. It is only one sided so I also use Our Side Notes tutorial for the double sided and pockets. Someday I'll make my own combining the two!
I found the fabric at JoAnns.