Are you wanting to build a round ball pouch, which is wet formed so that the shape stay even if it's empty? Or are you wanting to make just a pouch with drawstring to close the top? These are usually made with soft and pliable leather like elk, moose and sometimes thick buck skin.
The wet formed ball bags very often are made to resemble turtles with the dispensing end where the head would be. The person to ask about things like this goes by Cut Fingers. I will look for a pattern or a how to video in the meantime.
