COB spacing

The end game is to have 16, 3590 for a 4x4 footprint. I currently have 8 of them. What would be the spacing for them? The lights will be attached to angled aluminum. How long should I cut the angled aluminum and how far apart should the lights be? The driver will also be installed in the aluminum.
Thanks!!!

You are going to have 1 cob per square foot, so spacing is set.

and if you wanted the 8 in the same config to add more later, xo pattern where x is a cob, add the other 8 later on the o
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