It is lightweight and fits perfectly an Ocean Kayak Malibu II sit-on-top kayak. If you have a different kayak, only need to adjust the distance between holes in the frame to make it fit.
Enjoy it ;-)
Step 1: Materials
PVC pipes: 75 and 37 mm of diameter, about 1 meter of each one
2 screws with nut (M8x110mm) used as wheel axle
2 screws with nut (M6x80mm) to join the PVC pipes in a frame
Total cost of project: near 0 (just some cents to buy the screws)
Step 3: The parts
Cut 2 pieces of 37mm pipe, one for each wheel. In this instructable they are 420mm in length.
Dimensions and holes needed are shown in next step pictures.
Step 4: Assembly
At 25mm from the side of 37mm pipe, make a hole of 8mm. Use M8 x 110mm screws to attach the wheels to the pipes.
M6 x 80mm screws are located as shown in the figure to join the three pipes. The distance of the hole is 200mm from wheel side, and it has to be made perpendicularly to 8mm hole. It gives 220mm of tube that you have to pass through scupper holes in the kayak.
If you have a different model of kayak, probably you will have to change the distance between 38mm holes, to make them fit scupper holes of your kayak.