Motorcycle trailers are not complex accessories. A basic trailer for transporting one or two motorcycles consists of a platform and steel frame that's mounted on an axle. The size and type of wheels and tires is optional. The trailer has a ball hitch with a safety chain at the front and tail lights at each corner at the rear. Most cities and counties require a trailer to be registered with the vehicle department and bear a number plate. You can make a motorcycle trailer using welded steel channel iron and some plywood. The axle can be obtained from an auto wrecking yard.
Position the two-wheel automobile axle in an open area. Use a circular saw with steel cutting blade to cut lengths of two inch by one inch steel channel iron as a four-sided frame that will attach on top of the axles. Lay the frame pieces on edge with the wide section of the channel facing out and weld the four corners.
Cut four pieces of channel iron as cross pieces that fit between the sides of the frame. Space the cross pieces evenly within the frame. Weld them flush with the top edges of the frame to make a uniform surface for the platform.
Cut two additional lengths of steel channel to make arms for a trailer hitch. Position the pieces at the front corners of the trailer frame to form a triangle. Weld the end of each piece to a corner of the frame and weld the point of the triangle.
Turn the frame over and weld the top of a ball trailer hitch unit to the underside of the frame at the point of the triangle. Weld the end of a length of 1/2 inch steel chain to one side of the hitch unit as a safety chain. Turn the frame upright and position it on the axles. Align the frame on the axle and weld the frame to the axle.
Use a circular saw with a wood cutting blade and cut 5/8 inch plywood as the trailer platform. Position the platform on the frame. Use an electric drill with a 3/8 inch drill bit to drill pilot holes for 3/8 inch carriage bolts that attach the plywood to the cross pieces and each end of the frame.
Insert the carriage bolts through the plywood at each of the drilled holes. Thread locknuts on each bolt at the underside and tighten them against the frame with a socket and ratchet. Drill additional holes for eye bolts to use with tie-downs. Attach the eye bolts to the frame with locknuts.
Drill holes at the back corners of the frame to attach red reflector tail lights. Attach the lights to the frame. String the insulated tail light wires along the frame toward the trailer hitch. Use wire clips to secure the wires to the frame. Connect a brake light adaptor to the end of tail light wire leads near the trailer hitch.
Fenders can be fabricated using 1/8-inch steel plate.