Then I add the front wall. Before attaching it, I add a portion of the overhang structure. I made the walls 24”, maximizing material usage and providing proper clearance for the Arko-Mils storage boxes I plan on using.

Here is a close up of the front overhang partially built.

Here is a close up of the corner blocks.

Next I add the side walls.  Wherever there are exterior wall joints, I glue them in place with thickened epoxy.   For all other gluing I use Titebond III.  I use thickened epoxy because it seals the plywood edge grain, fills the gaps for sanding the joints smooth and is waterproof.  I use any leftover thickened epoxy for doing an initial filling of the screw holes.  

Now I move to the back for working on the rear / access door area. This is one area I wanted to get away from the basic box shape by having a sloped back and angled corner. I began by making and adding a portion of the rear overhang.

Then I added the main rear panels, they have a 10 degree angle to them.

To do the corners, I use a tape and glue method. The angle pieces are cut to size, shaped and then taped in place. On the inside fillets of thickened epoxy are applied to the edges. This glues the piece in place and provides a radius so fiberglass cloth can lay flat. Once the fillets get to the tacky stage, I epoxy fiberglass cloth over them to reinforcement the corners.

While the epoxy on the corner panels cured I add the door side wings and tapered panel above the door area.

Next I move to the front to add the nose box walls. I begin by fitting the walls, then flip the box on its side to install the corner blocks for mounting the walls.

Then I build and install the vertical panel under the front overhang where the nose box hinge will mount. 

Using thickened epoxy, I glue the nose box side and front walls in place.  Similar to the main walls, I use any leftover thickened epoxy for initial filling of the screw holes.

Next I build the nose box lid.  I start by making a frame that matches the nose box opening.  Its fun getting all the angles right, the top of the box slopes down 17 degrees, it angles in 30 degrees on each side and the outside edges are trimmed 8 degrees so they are parallel with the sides.  To glue the lid frame up I use thickened epoxy and tape the frame in place on the nose box.

Wanting some curvature to the lid, I made some curved frames and epoxy them to the top of the lid frame. For a little extra character, the curved frames angle in at 30 degrees.

Then I size and epoxy the lid panel in place.  After the epoxy dried, I rough sanded the edges and test fit the lid.

As the epoxy dried in the above steps, I worked on getting the main box top panel ready to install. Because the top of the trailer box is part of the sleeping platform, I added two cross braces space 16” a part. Being careful not to get any on the gluing surfaces, I sealed the bottom of the top panel and the interior sides of the main box with 4 coats of Target Coatings HybriVar (This has been replaced with their new and improved EMTECH 2000) a user friendly urethane waterborne borne alkyd varnish.

Now it’s time to attach the main compartment top panel.  As with the other exterior joints, I use thickened epoxy to glue the top in place.  Here is the method I use.  To ensure good epoxy penetration into the wood, I first coat both sides being joined with straight epoxy.

Then using a combination of Colloidal Silica (West System’s 406) and fine wood dust fillers, I mix a batch of thickened epoxy to the consistence of peanut butter.  This allows it to fill the gap well and hinders flow out of the join while curing.  Using a cut-off 1” chip brush, I spread it on one side of the joint area.

With the help of an assistant, I set the top on and use trim head screws to clamp it in place.

The tailgate is made by gluing two pieces of 1/2" Baltic Birch together and leaving a 3/4" step on three sides.

Here is the hole for the t-handle latch I’m using and the hinges. Initially I planned to used the hinge on the left, but switched to the stainless steel “gate hinge on the right due to clearance issues when opened. I’m also thinking about switching to a concealed piano hinge for a cleaner look.

Next it’s time to fill and sand, fill and sand, fill and sand … until the body is smooth.  Actually a quick final fill is all that is needed.  The Durabak I’ll be covering it in is very forgiving of surface imperfection because of its textured finish.

I like to make my exterior panels slightly oversize then sand them flush for a smooth transition.

After rounding all of the edges, I flip it over so it’s easier to do the bottom of the sides.

After sanding is completed the bottom and sides are sealed with CPES.

Next I fitted the nose box lid hinge and latches.

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