These flash compositions have a ten-minute time limit -- so every second counts. That's why I can get a lot farther into a sketch if it's just for a solo instrument. It takes just as long to write two measures of melody as it does for one measure of melody plus one measure of harmony (or counter melody). My musical training was as a keyboard percussionist, so I already had a pretty good idea of what's possible with a marimba (beyond mariachi music).
So what happens next? As with all the Diabelli Project sketches, that's up to you. If if inspires you, please feel free to make of it what you will. And please -- share the results.