We know of Balearic slingers as mercenaries from just before 300 BCE down to say 50 BCE; the islanders fought against the Roman expedition led by Q. Metellus in 123 and 122 BCE; the inhabitants of the islands are not mentioned as military slingers during the Roman empire, though Balearic as an adjective for the sling is used very commonly  in that period (e.g. in the poet Ovid). Of course, people certainly used slings on the island before and after the mentions of slinging in war.

There is no evidence for what the Balearic slings looked like during antiquity. What there is some references for  material: Strabo 3.5.1 C 168 mentions sinew, rushes, hair--

"On account of the same fertility of their islands, however, the inhabitants are ever the object of plots, albeit they are peaceable; still they are spoken of as the best of slingers. And this art they have practised assiduously, so it is said, ever since the Phoenicians took possession of the islands. And the Phoenicians are also spoken of as the first to clothe the people there in tunics with a broad border; but the people used to go forth to their fights without a girdle on — with only a goat-skin, wrapped round the arm, or with a javelin that had been hardened in the fire (though in rare cases it was also pointed with a small iron tip), and with three slings worn round the head, of black-tufted rush (that is, a species of rope-rush, out of which the ropes are woven; [and Philetas, too, in his "Hermeneia" says, "Sorry his tunic befouled with dirt; and round about him his slender waist is entwined with a strip of black-tufted rush," meaning a man girdled with a rush-rope), of black-tufted rush, I say], or of hair or of sinews: the sling with the long straps for the shots at short range, and the medium sling for the medium shots. And their training in the use of slings used to be such, from childhood up, that they would not so much as give bread to their children unless they first hit it with the sling.138 This is why Metellus, when he was approaching the islands from the sea, stretched hides above the decks as a protection against the slings. And he brought thither as colonists three thousand of the Romans who were in Iberia."

The quote from Philetas is probably an ancient gloss, interpolated in the text, so I've put it in square brackets. Virgil mentions flax:

Virgil Georgics 1.309
tum figere dammas,
stuppea torquentem Balearis verbera fundae,

Winter is the time to "strike down does, by twisting the flaxen thongs of the Balearic sling".

So it's a braided sling, made of fibre, hair, or sinew; there is no evidence for the actual design, but the well-known split pouch is at least likely.

Not exactly a sling description, but it helps give an idea of the technique.
Diodoros of Sicily, writing in the 1st cent. BC gives an account of the missiles at the Battle pf Ekonomos.
Book XIX-- "but when Hamilcar saw that his men were being overpowered. he brought up the slingers, who came from the Balearic islands, and numbered at least 1000. By hurling a shower of stones, they wounded men and even killed not a few who they were attacking, and shattered the defensive armor of most of them. For the men were accustomed to sling stones weighing a mina (1.25 lbs) contribute a great deal to victory in battle"
  With ammo that big, a split pouch seems to be the best choice, at least in my opinion.

I don't think they do, they're seen sideways on so they look like a single strap. The Etruscan tomb relief discussed on the forum a few years back seem to have a split pouch, but with a single strand across the middle, no ?

Quote:


http://perso.wanadoo.es/hondero/HONDASe.pdf