This has probably been posted before somewhere, but I can't find it and I guarantee that no one is interested in an old thread. However, a good canidate for sling tag ammo is duct tape and latex glove wrapped lead &/or pennies. they should be cylindrical.
1. Take used and deformed lead air rifle shot or shotgun birdshot, or pennies- about 8 of them per "tag glande".
2. take latex gloves and pour the weight in there.
3. take that glove and put in another (to take up space so soften impact). tie the open end of the glove. poke a hole in a finger to prevent air from getting trapped and letting all the shot loose.
4. wrap the gloves in duct tape. it should look like a piece of sushi- the one with the rice under the shrimp or fish- the seaweed wrap symbolizes the duct tape
5. take a patch of duct tape and cover the exposed ends.
6. wrap the almost finished "tag glande" like in step 4 to cover up all loose tape ends.
7. make as many as you need
this is just preliminary but they fit in almost anysling becasue of their shape. they wont break any bones or kill but you will definatley know if you're hit.