Mega Bloks is the place where I've learn packaging design. Here are a few boxes which, even after a couple of years, I still like to say : I've created those!

All the separators inside the box are made of cardboard too. 

Yep, round corners with cardboard! And a plastic cover, but this one was easy...

Huge barrels with 'in action' scene on top, super structure inside to hold everything.