I had been experimenting with stencils for a while to make small patches and customize shoes so I thought I'd go back to something I was more familiar with altering... shirts!
I started out cutting off the color and making this with somewhat of a tank top look, then wove the sides of my shirt all the way up. I unfortunately do not have any pictures on how I did this. You can easily look up a tutorial on YouTube or here, on Cut Out + Keep! :)
You can find a stencil online by searching "ribcage stencil." I saved it to my computer and scaled it to better fit my torso. This might take a few tries to get right.
Trace the stencil onto any kind of paper that is thin enough to be cut with an x-acto knife. I've heard freezer paper works great but with my impatience, I used tracing paper.
Place your finished stencil onto your shirt. I also put a piece of cardboard inside the shirt to keep the paint from bleeding through another layer and to keep the shirt from moving. To keep the design in place, use pins and/or tape (not too sticky!).
Use a sponge brush to CAREFULLY apply the paint then carefully peel off the stencil. The placement here is a bit off but I fixed this later by weaving one side of the shirt tighter.
Take this time to attempt any corrections where the paint may not have held. Let dry overnight.
And DONE! Enjoy :)