How long ring sling do I need?
Shoulder to Mid-hip (Diagonally) + preferred ring sling tail. (10-35 cm / 4 "- 14")
Usualy their lenght is between 60'' and 80'' (150-200 cm).
(2 x A) + B * see the picture
Sewing ring slings:
Although sewing a ring sling isn't too complicated, there are few thing to pay attention:
The ring slings are recomended to made from babycarrying wraps. An article about the usable fabric types:
http://www.sleepingbaby.net/jan/Baby/fabric.html
Thre are different types of shoulder types. You can read about them here:
http://babywearing102.tumblr.com/post/52795393030/ring-sling-shoulders
Be carrefull when you choose the thread and the needle, and for safety sewing. Before cutting pay attention to that you need 3.5''-7'' (10-20) cm longer fabric than your ring sling's final lenght.
Here is a great video about sewing:
https://www.youtube.com/watch?v=Qty_s3Y3sGU
Hungarian tutorial with pictures:
http://varrasegyszeruen.blogspot.hu/2016/05/karikas-kendo-varrasa.html