I started simply with large and medium puff balls, one big and one medium for each of the three colors, and had him transfer from the tray to the bowl. He did this work over and over and over and over... I am going to have him tong puff balls into ice cube trays next, 1:1 correspondence style.
His grip is more of a hand grip at times, but the more pincer-like grasp will naturally come with careful demonstrations and practice. He showed improvement with the grip just this morning (these photos are from our first session yesterday). Do you see the glaring problem in these photos though? Yeah, I didn't have him go left to right, the way Montessori does to train the brain for reading. When I demonstrated it was correct, I did it left to right, but he was on the other side so when it was his turn of course it was backwards. He chose this work again this morning and you can be sure I fixed the error!
Tonging is a great Practical Life activity for fine motor development, getting used to a scissor squeeze motion, as well as working towards a correct writing grip.