Sling projectiles
Pebbles
Then as now, stones are the most common and probably the cheapest type of sling projectiles. They should be free of sharp edges or corners, making pebbles a particularly good choice.
Clay projectiles
Projectiles made of clay are cheap and easy to produce, as well, and offer the advantage that their weight can be selected more precisely. Historically, these bullets were often simply dried or baked in a campfire. They could be produced in very large quantities. They often contained a "surprise" - Sharp stone chips kneaded into the clay increased their effect on impact.
http://www.youtube.com/watch?v=LBa1G12KyTM
At 04:30 min. the effect of such a clay projectile is visible.
Lead projectiles
In ancient and medieval times, sling projectiles were often made from various metals such as lead, bronze and iron, mainly for use in war. Depending on the design, their range was very considerable. Today's tests have shown that such projectiles could easily keep up with bows of the time in terms of range and power. Under certain conditions, they were even superior to the bow. The weight of these so-called "glandes" varies greatly, ranging from 40g to 300g depending on the intended use. Very light glandes were fired in batch. Now and again, inscriptions with insults or names can be found on ancient glandes. Some of these are quite macabre.
Rusty balls
Another type of inexpensive training projectiles are Rusty balls. They can not only simulate different shapes, but are almost indestructible as well, as they deform on impact. Afterwards, they can simply be kneaded back into their original shape. Rusty balls consist of a core of sand or wet clay, covered by several layers of balloons.
