There's lots of room for improvement before we get into fancy stuff like universal low-harmonics strategies (not realistic given the time constraints IMO).
[ ] Most importantly, come up with a better name
[ ] Multi-bot support (this is gonna be a complete rewrite since it requires proper timekeeping to keep bots from running into each other and to synchronize harmonics flipping)
[ ] More efficient bot movement (i.e. skip empty space, prioritize nearby plots)
[ ] Minimize the time spent in high harmonics.
For the last item, we can prioritize plots where every 'prefix' (i.e. lower part) is grounded. This way we avoid overhangs, however this case still requires intelligent bricklaying (the order in which we fill voxels within a single horizontal 3x3 layer is not arbitrary as some of them might be grounded only via their horizontal neighbours). Once we're done with those plots, we can do some of their neighbours which have now become prefix-grounded (bricklaying now has to take neighbouring plots into account). We can then generalize this approach: complete only the tallest prefix-grounded prefix of a plot, relocate somewhere else, then come back later to finish the job. Once we've exhausted this strategy, we can do the rest of the work in high harmonics.
There's lots of room for improvement before we get into fancy stuff like universal low-harmonics strategies (not realistic given the time constraints IMO).
For the last item, we can prioritize plots where every 'prefix' (i.e. lower part) is grounded. This way we avoid overhangs, however this case still requires intelligent bricklaying (the order in which we fill voxels within a single horizontal 3x3 layer is not arbitrary as some of them might be grounded only via their horizontal neighbours). Once we're done with those plots, we can do some of their neighbours which have now become prefix-grounded (bricklaying now has to take neighbouring plots into account). We can then generalize this approach: complete only the tallest prefix-grounded prefix of a plot, relocate somewhere else, then come back later to finish the job. Once we've exhausted this strategy, we can do the rest of the work in high harmonics.