Slings (no NOT slingshots) are actually awesome. It is very fun to learn to throw tennis balls. The average physically active adult can with learn to throw without hurting their bodies at speeds only a fairly professional baseball pitcher could rival with arm alone. The "lever action" you get from the slings length translates to a much slower (angular rotation) and less violent acceleration necessary at the base of the rotation (your body) for a vigorous throw, it doesn't hurt to throw even fairly heavy things because it is like you have gone to a really low gear on a mountain bike.

I really like this guy's paracord slings, might be expensive but you are also basically buying a template and a tool that will last for years and years of throwing.

https://www.practicalparacord.com/

https://www.etsy.com/shop/PracticalParacorded?ref=shop-header-name&listing_id=1400323503&from_page=listing#items

https://youtube.com/@practicalparacord

Montage of normal people slinging and the crazy variety of body types and throwing styles, I have never seen a sport/throwing implement with such variety of body mechanics, it is clearly in our bones after all, to make a sling simply requires cordage of some kind, time and a pile of rocks!

https://youtu.be/qVrWk557reU

Prior to Goliath David was using that sling to defend his flock from wolves. I imagine it's much harder to bullseye a running wolf than human with acromegaly like Goliath.