The placement problem, according to systems made with plasma balls, can be easily solved considering a 2D map, within a bidimensional matrix, and adding, subsequently, another ball, a couple or even more, on top of them in a 3D spatial structure that will carry their relative proportions.
No one has even considered this concept deeply enough, whilst working with ready made balls. Proportions, 1/2 1/3 1/4 1/5 1/6 1/7 etc... of various ganses, cosidering too the impossibility to weight them exactly, that makes things even less scientific from a "play it again..Sam." point of view . The number of reactors, for example, starting from a minimum structure of 4, could reach hundreds. So, here are some examples, that you could use to find out what happens whenever you place your reactors in such a way. This, is just a starting point. Once you understands, and compare results, you shall stack them one on top of the other, and build multiple ones if needed.