Rope sandals have been around since the late 1960s. They became popular because they are lightweight, washable and can be worn anywhere. They are also very simple to make, as the process involves only cutting pieces of rope and melting them together. You shouldn't use just any type of rope, however. Polypropylene rope should be used because of its lightweight, comfortable feel and low melting point.
Take a large amount of polypropylene rope and cut out 5 to 10 pieces a foot long each. Lay enough pieces side by side to cover the entire width of your foot and form the sole of the shoe. You may want to tie these pieces together with string or yarn to hold them in place, but you won't need to keep the string on for very long.
Cut the sole to match the length and shape of your foot. You'll only need to cut them at the ends of the ropes and not the sides. Approximately match it to the shape of your toes and heel.
Melt the ropes until they are fused together. Polypropylene rope melts at about 150 degrees Fahrenheit, so any type of lighter should work. Heat the ropes slowly to fuse them together strand by strand. Remove any string you used to hold the unmelted ropes in place before heating the area.
Wrap another piece of rope around the circumference of the soles you just created. Melt and fuse this rope to the soles to form an outer edge. You may want to create a second layer by repeating all the above steps and melting the two layers of soles together.
Add the straps to the soles. This is where you can get creative. You can use as many rope pieces for straps and overlap them in any way you want. Just make sure they're at the right height and arch that your feet are comfortable while wearing them. Melt the edge of each strap to the outer edge of the soles.
Repeat all of the above to make the second sandal.
You can give the sandals "hard soles" if you want. Apply a layer of "shoe goo" adhesive to the bottom of the sandals and let it dry.