In this instructable I will show you how to make a tool-box seat for your van.
For this project you will need:

2*2 white deal (or other type of soft wood).
3 sheets of 12mm marine plywood 4ft * 8ft.
Screws 60mm, 40mm,18mm, wood adhesive.
Screw gun, skill saw, orbital sander, jigsaw, clamps, measuring tape, pencil, spirit level, adjustable bevel.
4 hinges, lock , brass screw cup (decorative purpose).

Before you start take the measurements of the space and size of where you want to fit the box. Remember "measure twice do the job once".
Most important: WORK SAFE.
Use all protective gear: gloves, eye and ear protection.

Step 1: Making the Box Frame

Make the box frame using the dimensions you measured for the box in your van taking into account the height comfort for your legs. The front of the box can be flat or beveled.
Under the long horizontal span add support.
Box front vertical support cut in an angle.
Screw 2*2 inside the box for the inner shelf support.
For all screws drill pilot holes in the 2*2 frame.

Step 2: Plywood Cover

Use the skill saw to cut the plywood for the box walls.
Screw all sides into the 2*2 frame.

Step 3: Opening for Shovel and Long Tool Storage

This will be at the side door - easy access for the tools.
Use the jigsaw to make the opening on the side.

Step 4: Inside Shelf, Plywood Cover

Measure the inside of the box ,cut the plywood and screw the sides in. Don't screw the shelf you will need access to the base when attaching it to the van's floor which also leaves you with easy access to clean the shelf or to reach the bottom of the box.
After the inside is done cover and screw the box top sides with plywood (measured cut to size).

Step 5: Box Base Cover

Screw support for the inner 2*2 at 45º on all sides (in my image you see only one side), use glue for extra strength.
After cutting plywood to size screw it to the box base. The base will be used to attach the box to the van's floor so don't be "shy" with the screws when attaching the base plywood.

Step 6: Lid Support

Screw the 2*2 inside the box to support the lid.

Step 7: Attaching the Lid

Screw the back part of the lid.
Lid is made from 2 layers of plywood for extra strength. Glue 2 layers of 12mm plywood and clamp them together until the glue is dry.

Step 8: Attaching the Hinges and the Lock

At this last step fix the hinges to the box lid, leave a 3mm gap from the back lid.
Chisel the lock depth and attach the lock.
Round the lid corners with a jigsaw.
Sand the box with an orbital sander or corner sander for a smooth finishing.
Paint the box or leave it natural.