While flexible pixel strips are the easiest to use for building your pixel tree, they are typically spaced fairly close (between pixels) ... so this creates a high density in one direction and typically a much lower density in the perpendicular direction. So the typical model has strips used on vertical supports or straps using say 1" spacing, but if you put 20 of them across your 180, then you horizontal density is less if you calculate the space between pixels. Anyways, there is not right or wrong way -- they all look stunning, IMHO . There is always a cost vs. labor equation to every design ... and you have to figure out which is best for you. Beware of flexible pixel strips which turn on groups of pixels, as those are not a good choice for pixel trees. It is better to have pixel (node) level control if possible. And 12v is more common in this forum as stated already -- because the smart string gear uses 12v injection using common ATX single rail PC power supplies -- a great and simple design IMHO.