A simpler way to do this would be for the user to create and place some temporary virtual "grids". For example, the user might create a virtual triangle of a certain size. Or in the case of this request, a circle with n points. Note that these are virtual and temporary items never created in the underlying tikz code (though you may implement them with hidden tikz code).

Then the user can do one of two things. (1) Select an item and place it on the grid, and the item gets replicated on all the grid points. (2) Pick and place different items on each of the grid points.