Lay bras flat, with molded cups facing up. Stack the bras on top of each other, so the cups sit inside each other, to keep their round shape. Keep the bands and straps out until you are done stacking. Then, tuck all the bands together into the cups of the last bra. Store your molded or full coverage bras on top.
The case is fairly rigid, but could crush with too much weight. We suggest making sure it is below the top level of your soft sided suitcase and not in the expanded area with no protection if checking bags. For nearly all other use, it will be just fine.