Sidenote:Sorry(not really) for the not so grand photo quality. I was too lazy to find my camera & just used my iphone.
white eyeliner(or some light colored pencil)
(I picked up this sweet tie dye graphic t from my local thrift store.)
I used another muscle tank that I got from Forever 21 for my guideline. I didn't want to make the sides too long, so I needed something to go off of. Use the measuring tape if you want your tank to be some what symmetrical. After I placed the Forever 21 tank on top of my new tank, I lightly drew around it so I could have a pattern & guideline to follow when I cutting my shirt.
I'm actually going to wear this muscle tank to work tomorrow, here are some necklaces I plan on layering with it.