I did this one with Christel on a very hungover day after way too much shopping.
For this DIY you'll need:
Scissors, an old tee, mesh fabric in the same color, pins, needles, thread, and preferably a sewing machine.
Cut your tee where you want to insert the mesh part, this can be anywhere you want. Around the boob area, above it, underneath it, 2 parts, in the sleeves, etc etc
Now cut a rectangular piece of mesh fabric and sew it in-between the two parts you just created.
And this is what you should end up with!
Note if you take a very narrow tee you might want to consider adding zipper, or just use a wider tee.
Too lazy to do it yourself? Here are some of my favorites.
