Thought I'd upload my slings so far, with tennis ball for size reference, beginning with my first functional sling;
Un-prepared sisal twine (with inverted fleece retention loopcovering sewn on):

"Craft" cotton (used this one for a few weeks and featured in my two previously posted videos):

Acrylic 8 Strand "round braid" (Made this one about a month ago, been very happy with it's performance):

Acrylic Balearic style (Literally just finished, as yet untested):