the best would be:
- a quick release snap shackle at one end (see image, you only need to change the small red rope to make it easier to grab in emergency), more info on that shackle on:
http://www.wichard.com/fiche-A|WICHARD|2673-0202040301000000-ME.html
- then a ~ 2m long (shorter or longer depending on your preference) dyneema rope (~8mm diameter) that you eye splice at both ends
- then you sew in the middle of the dyneema rope, some ~2mm shock cord
- then at the other end, you add another rope (thinner ~ 3mm dyneema) eye spliced at both ends, that will loop into your safety system: you only need one safety release close to you, and you don't have the risk to injure your hand with another shackle close to the bar when doing handle passes!
the only problem is that such shackles are pretty expensive in OZ...so I did my leash with the cheap version (not as safe) as suggested by GalahOnTheBay.
if you really want a nice finish, you can add a protective braid form a thicker rope (~12mm diameter) on the top of those ropes
then you have a light, safe & super strong leash!