Depending on how big you want your vault box, it will change the amount of wood you will need.
For a 3 foot tall vault box you will need:
6 8ft 2x4s
Two sheets of ¾” 4’x8’ plywood
32 truss connector plates
Construction grade polyurethane
Bunch of nails or wood screws (T-25 star bit recommended)
Nail gun/hammer or power drill for screws