FlatPak™ Toiletry Bottles

The flat shape really does save space in my Dopp kit, I fit three of them where one round bottle used to go. Filled one with conditioner and it didn't leak on a four-hour flight.

Squeezed a full two weeks of shampoo into one of these and it never leaked in my carry-on. The soft sides mean you can actually get the last bit out instead of throwing away half a bottle. TSA didn't blink at them either.

These things are genuinely genius for packing. I fit a full 90mL of face wash in mine and it took up maybe a third of the space my old hard bottles did, no leaks at all on a two-week trip.