first off, thanks for the compliments.
im not sure what kind of fabric it is. all i know is its stretchy. aha.
but heres a quick tutorial and the whole thing is just a bunch of tubes really.
1. i simply measured around the bust and then made it 12 inches the other way. i folded it in half so it held better at the top so now its 6 inches. and then i sewed it.
2. then for the body part im not sure how wide mine is but thats really up to you. but its just a tube gathered in a random places really. there was no thought put into where the gathers would be.
3. i then made a tube at about 24 inches in length and about 3 inches (when folded so 6 really) in width and turned that inside out.
4. when you sew the top to the bottom, one side of the strap is going to go inside and the other side is going to go outside.
heres a quick little picture to better understand this.