a t-shirt, I got mine from The Dollar Tree. It should almost be a little "too" big but doesn't have to be. scissors, sewing machine (or good old needle and thread), strips of lace (optional... if your t-shirt is not big enough)
1. cut neckline as desired. I cut off just the hemline of the neck on mine.
2. cut sleeves as close as possible to the seam.
3. fold your shirt in half so that both sleeve holes are touching each other and make a crease (using an iron) up and down the back only.
turn your t-shirt inside out. (it will remain this way until you sew it back up)
4. cut both sides, the entire length, from right under the armpit to the end hem.
5. now cut the back middle, starting from the bottom and stopping about 2 inches before you reach the top neckline.
6. twist each piece 360 degrees (either into each other or away from each other)
7. pin both sides back together and sew.
OPTIONAL LACE: add a strip of lace (as thick as you like, I cut mine about 2" wide, which lost a little bit of width after I sewed it. also, if you saw my picture last week, it doesn't have the lace. I did it as an after thought after I realized the back didn't look quite right. I realized it lost some width after twisting and sewing in 3 sides that were previously not sewn)
8. pin the back, starting from the bottom and stopping where desired (I made sure to stop mine right after my bra strap), and sew.
I'm pretty excited about how simple this was and hope I get lucky at finding another super cheap t-shirt.