DIY make your own shirts for cheap! All you need is an old t-shirt and expensive laser cutter.
Seriously though if you want to try this, 100% cotton washes out. We had luck with 60% cotton 40% polyester. Let me know if you experiment with other materials. Also remember to de-focus your beam.
Filming and art by CameraManJohn: https://www.johnwillner.com/