Braiding an unbroken piece of leather looks impossible but is really easy once you know the tricks.
My definitions (I don't know what the proper terms are so I gave them my own names) -
Point - The end of the leather farthest away from you
Bottom - The end of the leather closest to you you
Bow - The opening made when you push two strips to the side
Practice on a strip about 2'-3' long. Longer than that and it gets really confusing as to what is what. Shorter and it's not worth the trouble.
A leather strip about 3/4" wide is perfect. Slit it into 1/4" strips being sure to leave 1/4" - 1/2" at the ends.
Work the leather bending it back and fourth until it's soft and flexible.
Step 1: Marking the Leather
Hold a pencil or pen like this and use your finger as a guide while marking the leather into thirds.
Step 2: Cutting the Leather.
A sharp utility knife cuts leather very well. Use a new blade.
I found the best method for me was to push the point thru the leather into a piece of scrap wood then very slowly and carefully pull the leather thru the knife instead of moving the knife.
Step 3: Starting Position.
Start with your leather in this position. The bottom is to the right of the photo.
Step 4: Starting to Braid
To start push the center strip to the right, then reach thru the bow and pick up the point.
Step 5: Pull the Point Thru the Bow
Then pull the point back thru the bow. As it comes back pull it back straight. It may feel or look like it's tangles but on the next braid it should straighten out.
Step 6: Second Braid
Now push the center strand to the left and reach thru the bow and pull the point back thru just like you did on the last step.
Step 7: Continue
Continue to alternate the left braid and then the right braid until you finish the strip. If the braid is unbalanced at the end you should add one or take away one.
If it's not smoothly braided you can work it back and forth to even out the tightness of the braids.
This last photo shows a braid finished but not smoothed out.
If you want to unbraid it just reverse the steps you used.