The leash that I am showing you to make is suitable for a SMALL to MEDIUM sized dog ONLY!!! Don't go walking your 150 pound Bullmastiff with it because it will break when the dog strains on the leash. If you want to make a stronger dog leash, double up the braiding strands or use a thicker plastic.
Since this project is braided with all the strands being the same colour, it might be confusing to one that is just learning how to braid. I have made another four strand braid instructable where all the cords are different colours. Check it out if you need help starting or finishing your braid.
The reason that I really love Instructables is because other members are constantly giving feedback on your design and perhaps on how to make things better. jtobako queried me on the snap attachment and said it looked a little weak, which was a really good point. I haven't had a problem since my dog isn't really a "puller", but it did get me thinking. I did come up with a sturdier way to attach the snap to the braid, which you can seen in steps 20 to 23.
I have just started up my new blog Bloggie Stylish where you can find all kinds of neat tutorials, like this one.