My first sling was one of these my that brother made for me
http://www.youtube.com/watch?v=APExNLO1oHYbut it was to small and didn't hold rocks very well.
Anyway, I forgot about it when I got my Aussie pouch
After that I started experimenting with lots of different slings. My first successful sling I made myself was a simple sling made from some old jeans, which worked quite well in the beginning, after a while it tore up.
Aha, found an old, really bad, picture of it.
These were the first slings I made.
they are all long lost and gone, except the immortal aussie pouch