You will need a espadrille sole and a string to make the eyelets of the sandals.
You can see how to make the sole on the images.
Once you will have the sole, with different strings you can make lots of combinations.
Step 2: One Espadrille Sole - More Than 20 Different Sandals
To make the sandals you can use one espadrille sole. With a string, you have to make a couple of eyelets as you can see on the image.