It's super easy.
All you need is a Tic-Tac box, or any other box with a flip up lid, a nail polish; it would be best to use one you don't really like, I used a cheaper brand but still in my favourite colour, pink, this is because you will need to use quite a lot of paint, and bobby pins.
Take off the white lid/cap thing and paint the base of it, try not to paint the top, but if you do accidentally you can just use some nail polish remover.
Quickly put the lid back on the box and leave the paint to dry, this will act like a glue to stop the lid coming off when you get out your bobby pins.
Now paint the rest of your box however you want, you can do a creative design or a simple colour like I did. Again try not to paint the lid because it can make the whole box look messy, however you could experiment with different colours but you will need to be really precise with that.
Wait for it to dry and put your bobby pins in it. Don't over fill it because else you wont be able to get your bobby pins out again.
Whenever you need a bobby pin just flip up the lid and tip it out. And they are the perfect size to take anywhere.