Have a go at making your own sling....from paracord.
Cord is £5 ish for 100ft.....loads of colours available including camo of three or four shades.......plus price of clips about £12 ....and a bit of tourettes when you start !....and about 2 hours of your time.
you will have some over to make bracelets and key fobs or short zipper tags....which end up in a square section of weave....
you wont find stronger and they look the dogs danglies !
Go on ...have a go ?