What is the physics in a balero toy? A balero is a wooden ball tied with a string to a rod. The string ties to the ball at one end (say North pole), and there is a hole drilled in the ball at the other end (South pole). The hole is the same size as the end of the rod.

The object of the game is to swing the ball, and give a slight flick on the upswing, letting the string go slack at about the same time. The ball goes up in a parabolic arc, but the flick causes enough rotation so that by the time it is descending, the hole is facing the person, so that they can catch the ball on the stick.
A description (with images) is given here (in Spanish). A similar game is described in the English wikipedia here but that is not the same.
At first it seems impossible, because the ball always seems to face away from the player, but after some practice it becomes possible, until finally it is a repeatable action! I remember I managed to get 8/10, but now that I think of it, it seems very difficult to understand how a flick would cause the ball to rotate so much. I don't have the toy any more, and was thinking of building one. I was wondering if there might be some trick to building it, or if it is just plain physics.
 A: No tricks needed. You can make it basically without a special design, as long as it follows the general guidelines: piece with hole tied with string to piece with rod. Of course the hole should be a fit loosely the rod. As for string length, it should allow movement of the dangling piece, and the shorter the harder it will be to master.
As for the physics, well there are many movements you cause on the dangling piece, but all of them cause a similar situation to this: you make it start moving with some acceleration by moving the rod, which will cause a rotation component with the string tense. When you suddenly change the movement of the rod, the dangling piece will continue its movement which includes rotation, and this will make the hole visible and reachable with the rod. Some times you even cause this rotation by starting from the position where the dangling piece is resting on the rod, and no tension in the string will be mandatory to make it rotate and fall back with the hole accessible to the rod.
