Buy some leather strands in your favorite jewelry material store or other craft store.
Definitely take more than one color and take about 2m per color - that way you'll definitely have enough for more than one bracelet and some extra.
You'll also need specific clasps and jump rings that look like this before they are used:
Then you need to measure around your wrist. I just used the leather itself and took three strands at a time. Clasp them together at both ends, insert the jump rings and of course a closure and you're done! Fast and easy and perfect for summer!