Outdoor Life Online Editor

Having trouble finding a securable chest that is just right for your guns? These plans show you step-by-step how to custom build a weatherproof lock-box that will keep ammo and firearms safe at home or in transit. It can be bolted or cabled to the floor of a car or the bed of a truck. Just like the whitewater dories I have designed for “Do It Yourself,” this lock box is constructed from epoxy-sealed plywood reinforced with fiberglass, and it can be easily customized to fit any gun from a semi-auto handgun to a rifle.

Step 1:
I designed the plans here to hold my Model 29 Smith & Wesson .44 magnum, spotting scope, binoculars and several boxes of ammo. You can adjust these dimensions as you need for whatever arms you wish to secure.

Cut out the main box pieces from 3/8-inch thick ply: bottom side, 151/4 x 24 inches; left and right sides, 91/2 x 15 inches; front and back sides, 10 x 24 inches; and the top, 16 x 24 inches. Trim all the edges with a block plane. Apply epoxy to all the mating surfaces of these parts (see Materials list) and glue the box body together, creating a closed, sealed form. A minimal clamping pressure is recommended for the epoxy, and weights work as well as clamps to secure the contact surfaces.

Step 2:
Round all the outer edges using the block plane and sandpaper. Apply fiberglass cloth to all the flat surfaces, and then apply three-inch-wide fiberglass tape to all the edges (all the surfaces are covered with fiberglass cloth, including the bottom, and tape along all edges and corners).

Step 3:
Draw a pencil line all around the top of the box, two inches down from the top edge. Then drill a small hole on the back side to insert the jig saw blade and saw all around the box along the marked line, cutting off the top lid.

If you want to hinge the box top with a single piano hinge, however, drill and attach this in its exact spot on the backside of the box after you’ve drawn the cutting line. Then remove the hinge and cut the top off. When re-attached with 3/8-inch brass wood screws the hinge should align exactly.

Step 4:
Cut four 3/4 x2-inch timber cleats to length and epoxy them in place inside the box around the lid opening so that 3/4-inch of each cleat stands above the top edges of the box sides. Round the cleat top edges slightly with sandpaper. Seal the interior of the box with two coats of epoxy.

Next, apply beads of thickened epoxy to the interior corners of the main box body and the lid. Spread the beads with a mix stick or suitable round paddle into a concave “fillet”-a curved layer of epoxy running the length of each interior seam. The fillets reinforce and help waterproof the box.

Step 5:
Install a 1×3-inch locking hasp on either side, left and right, using the brass wood screws (see photo). When secured with a small padlock these will prevent entry even if the back hinge is removed.

Campaign chest handles placed on diagonal corners provide best balance for lifting the loaded box. Attach these with the wood screws. If designing a larger, heavier box, you may want to use bolts to secure multiple campaign chest handles.

Drill holes through the box bottom for a locking cable or bolts. Cushion the bottom of the box with foam or fabric of your choice. I simply folded in some fabric, or you can fold in a thick towel. You can paint the box to your tastes.