One of the drawbacks to a bicycle is that it lacks the storage space of a car or truck. A bike trailer is one of the solutions to that problem, and a lot of bikers have made their own out of various materials. There are a few different ways to build one, allowing flexibility in design. The trailer hitches to the back of your bike on a flexible pipe, and follows the every move of your bike.
Sketch and brainstorm the trailer you will need. Different trailers have different functions. If you need a high-sided trailer for carrying smaller objects, you should design it as such. Alternately, a shallow trailer can hold larger objects, or could have a cooler strapped to the top.
Cut lengths of PVC pipe for the wheel axles. The pieces should fit into two T-joints and leave space for the wheels, for example if your tire is 1 1/2 inches wide (on the axle), cut a piece which is 3 1/2 inches long. You need two to act as axles, and four to act as fender struts.
Cut the fender walls out of PVC pipe. These should be the as long as the diameter of the tire, and you need four for each tire, eight in all.
Build the fenders by dry-fitting the parts together. Fit the pieces together without glue. Fit a fender strut into a 90 degree angle joint, and a T-joint to the other end. Place two fender walls into these pieces parallel to each other. Make two of these pieces. Fit the wheel on the axle, and put it between two T-joints. Attach this to the wall pieces on both sides, so that the 90 degree joints are along the same tube.
Build a second fender.
Build the trailer hitch. Cut a 3-foot length of PVC pipe, and a 1-foot length. Dry fit these to a 45 degree elbow.
Drill a hole through the end of the 3-foot length on the hitch, about 1-inch from the open end.
Cut the rubber tubing into a 1-foot length. Insert a 3/4-inch washers into each end of the tube, and push them in about 1 1/2 inches. Punch a hole through rubber so it goes through the center of the washer. The washers provide a rigid hole to punch through, and strengthen the hose.
Insert the hose into the end of the trailer hitch, so that the holes line up on the rubber tube and the PVC pipe. Insert a bolt through the hole and attach it in place with a nut. This forms the coupling.
Build the bottom frame of the trailer according to your sketch. Make a rectangular frame to the size and shape needed. Make several beams which run across the bottom so your trailer has a platform. Dry-fit pieces according to your needs. The trailer should not be more than two feet wide so it doesn't interfere with other traffic.
Replace the bottom left and right side pipes of the trailer with the fenders. Cut the front pipe in half and attach a T-joint to it, then plug the trailer hitch into that. Position that at a 45 degree angle.
Use PVC glue to attach all of the pieces together. Most PVC glues use both a primer and glue. Paint the primer inside the joint and the glue outside the pipe. Push the pieces together and give them a quarter turn to set the glue. Leave the glue to dry overnight.
Unscrew the bolt on the coupling, and wrap the hose around the bike seat stalk. Push the two washers back into the end of the pipe and reattach the bolt.