I spend a fair amount of sleeping time in swags and the best basic style aussie swag that I own was made by Flemming and Sandford.
It's made from heavy duty canvas but is more flexible than some others which feel like they're made from hard cardboard.
The design of the flaps and fastners etc are very good and it does work well.
Not sure if they still make that style or even if they are still in business.

Beware of those mozzie proof designs if you ever hunt the top end in the heat.
Some use triangle shaped canvas side panels with a net roof that you have to tie up to something.
The canvas side panels do not allow any air or breeze through and can be as hot as hell if used in the tropics.
Much better to use a basic style swag and a lightweight net hung over it which will allow more air flow.