1. 2- Pallets (Free if you shop around)
2. 2-3 hinges $3-$4
3. Circular saw blade (going to get trashed)
This one is a bit unique, if you have never tried to tear apart shipping pallets, it's not easy. (I would rather dig a ditch)
It is easier to cut the pieces apart instead of trying to pull the nails. The treated lumber will kill a saw blade.
The length of the cut boards determines the length of the box.
I used a piece to run up the interior back and lid to add support.
Fog piped inside can also add to the effect.