So this is my first attempt..i'll share it here because it's so easy i bet anyone can do it too..
Start with a couple of t shirts of the same or coordinating colours. Dig into your old clothes. Or you can get these cheap anywhere. This project work best if you use cotton knit shirts. These shirts I used were actually one of mine and one of my sister's that i accidentally brought to london because they are identical. (sorry Acah, klong gunting baju Acah! hehehe....)
Cut the extra shirt into strips of 3.5inch width (If you're not making a nursing top you can use narrower strips). I have 3 strips here but I actually cut 4 (the fourth not in photo).
Sew the ruffle on. The great thing about working with knit (t-shirt fabric) is that knit doesn't fray. So you don't need to hem, or finish the raw edges of your fabric. Put the shirt on and mark two horizontal lines where your breasts are. You probably have to enlarge the photo to see my lines there.
Continue with the third ruffle. Cut the horizontal line that you marked earlier (remember knit doesn't fray but you can sew zigzag around the 'hole' if you like). I didn't and it's holding up great. I also added a fourth ruffle underneath but didn't have any photo of that.
Here's the result;