Step 1: Parts
4x4 plate (one)
1x2 tile (ten)
2x2 tile (four)
1x2 brick (ten per layer)
2x6 plate (six)
minifig holding item to be contained in the box (one)
Lining the bottom with tiles will help keep the small parts from sticking or getting stuck inside.
The 4x4 plate helps keep the lid in place and holds pretty strong, I can turn the container upside down and nothing spills.