This method of constructing solid, wooden sides for a small utility trailer uses a minimum of materials and requires only an hour or two for assembly. We found all these materials on hand in the shop. This concept may be adapted for trailers of other sizes or where other materials are available for use.
Step 1: Fabricating the Sides
Determine the desired height of the sides. We chose 16 inches simply because there was a supply of +/- 33 inch plywood on hand in 3/4 inch thickness. The boards are first ripped to this height (width), then cut to length. The front and rear boards run the full width of the trailer while the side boards butt up against these. This allows for more fore/aft strength and security.
Step 2: Constructing the Corners
2x4 lumber cut to 16 inch lengths are then nailed to secure the corners. The face of the board is attached to the sides while the shorter sides are attached to the front and rear panels (see photo). We used 2 and 2-1/2 inch nails for this step.
Step 3: Securing to Trailer
Simple plywood flanges are cut about as wide as the trailer and 6-8 inches in height. These are attached to the front and back panels and extend downward to the bottom of the metal frame of the trailer. We used nails temporarily but replaced them with hex bolts, nuts, and washers. We used around 4-5 bolts to secure flange to plywood side and to 4-5 more to secure flange to trailer steel. Repeat on the other end.
Step 4: Completion
Here is the completed project (excepting bolts which were added to both front and rear flanges later. The wood could certainly be waterproofed and/or painted for durability, a lid of some type could be added, and other customizations are possible for specific purposes and are limited only by the imagination and common sense.
Completion time: 1-2 hours
Cost: $50-75, depending on materials chosen