Dogs are naturally energetic and strong animals. People have been harnessing these attributes for centuries and employing dogs to pull simple dog carts carrying various items, or even people occasionally. You can build one of these dog carts that is perfectly sized for your dog's weight and height. The cart is then attached to your dog via a harness that distributes the load across his shoulders and chest. The construction is simple and uses basic materials, some of which you can even recycle from old, unused items like strollers and bicycles.
Arrange four 1¼-inch-diameter PVC pipes in a square shape on the ground. The pipes should be as long as you want the cart to be.
Slide a PVC tee fitting onto the top and bottom pipes of the square. The single opening side of the fittings should be facing toward the middle of the square shape.
Fit a fifth piece of pipe into the openings of the tee fittings. This pipe will split the square shape into two rectangles.
Connect the corners of the square shape with PVC 90-degree "Y" fittings with the vertical openings facing upward.
Drill through the exterior side of the two tee fittings with a power drill. The axles for the wheels will be inserted into this hole, so drill the hole just big enough to accommodate your metal axle rods.
Insert the axles into the holes. Use a mallet to force the rods securely into the fitting.
Slip a washer and spacer onto each of the rods.
Mount the bicycle wheels onto the axle rods and secure them with the wheel nuts.
Insert four PVC pipes into the vertical openings of the "Y" fittings. These are the front and back of the cart, so make the pipes as tall as you want the frame to be.
Attach elbow fittings to the ends of each of the vertical pipes. The fittings should be positioned so the two behind the wheels are facing and the two in front are facing each other.
Insert lengths of PVC into the two sets of elbow fittings.
Cover the base of the frame with a piece of pegboard. This board should be attached with a power drill and screws.
Stand before the cart so the wheels are on the right and left and mark the point halfway up the vertical pipes on the front with a marker.
Screw in large eyehole screws into the middle point of the front pipes that you have marked. You should end up with the eyehole openings facing upward rather than to the side.
Secure the back of the screw with a nut on the back of the pipe.
Insert another two eyehole screws into the lower front corners of the frame, so they are vertically aligned with the other set.
Insert hook screws into one end of each of the two wooden dowels.
Place the hooks into the eyeholes and tighten them with pliers.
Screw a hook or clip into the other end of each of the dowels. These will connect to whatever harness you use for your dog.
Look for a jogging stroller or bicycle at a junk sale for a cheap way to get the wheels.
Do not put very small children on the cart because they won't be able to support themselves and may fall off.