DIY Tee to Cut Out Bandeau Top Tutorial from Bleached Faded here. Really easy tutorial although Id probably sew wear she has used fabric glue. I would also again wear a tank top or something under it so it's more modest.
Make sure you use a t shirt with very thin, light material. I used a band shirt because I thought it would be so cute but it ended up being thick and stiff. It definitely was easy though! -TM Cute bathing suit cover up:)