I never would have thought to put spinning tops on toddler (Montessori) shelves if I hadn't received a little wooden handcrafted top (below) from a friend. When Otis was younger I presented spinning tops in a tray, this is a good option for a child learning to use the tops as the tops are contained in the tray and the child doesn't need to spend all their time picking them up off the floor. You can see how I presented them in a tray in this post at 38 months.
Now Otis is pretty good with the wooden top and he uses it directly on the table top. The little metal top has a finer point and is a little more difficult. I love having these little tops around as they are almost irresistible, when you see them it's hard not to pick one up and give it a spin.
They are really good for both of my children who are learning to write and need further coordination and strengthening of the hand and fingers. They are also lots of fun on a rainy day.