mab

I have a 3D grid of 100mX100mX50m, with 4m intervals among all the points. On the other hand, I intend to copy this small 4mX4mX4m block onto the grid to form a massing. The problem is I want fixed number of blocks copied which is about half the number of all the points in the 3D grid. SO how do I create iterations of different ways of arranging this fixed number of blocks within that 3D grid, in order to have different results of massing.