Drive NeoPixels in a 2D arrangement as one virtual strand
Take a NeoPixel string, cut it up, and lay it out in a 2D layout of strips. This drives the pixel colors in a "virtual strand" that is as wide as the horizontal dimension and is replicated vertically.
An application is to use the NeoPixels to highlight a poster. By using the virtual strand, the standard NeoPixel demonstrations of color wipes, etc. Just Work.