Here we go, step by step

1) What you need:

     30" Lowes toolbox
     thin rubber pad
     one layer of 2" dense grey foam
     one layer of 3" dense grey foam
     Electric carving knife or Box Cutter knives (with the break off blades)

The Foam can be bought at www.canalrubber.com or most hobby or sewing stores.

2)Take the thin rubber, and pad the bottom of the box

3)Take the 2" foam, and place your lower onto it.

4) Trace you lower as shown. It is advisable to cut the foam a little smaller than the lower to provide some tension to keep the lower held in place.

5) Cut out the area for the lower using an electric knife or sharp exacto knife. It is recommended to allow the foam to sit in a freezer for a period before cutting to make this task easier. When cutting, keep the knife vertical to ensure a clean look when finished.

6) Take the 2" piece, and place it onto the 3" piece. Then trace the hole and cut it out of the 3" piece.

7) Place the 2" piece in the bottom of the box.

8) Test Fit bottom foam in box with the lower as shown.

9) Place the 3-inch foam into the box and place upper on top of it and trace.

10) Remove the foam and cut out as before.

11) Place the 3" foam in the box on top of the 2" foam. and make sure that everything fits as expected.

12) Once you are happy with the fit, remove the foam pieces and glue them together with a spray adhesive like 3M #77 spray cans S/B available at Home Depot. When done you can reassemble the toolbox and use the tray as a cover!

Other comments from Cincinnatus ...

The Upper and lower will not touch due to the differences in thickness in the foam pieces. If someone intend to store (not just transport) a rifle in such a box, It is advised that you put in a desiccant pack/device.

Cincinnatus has another Toolbox Project on the Maryland AR15 Shooters Site