I show and tell others wanting hard(er) buds to simply hand compress them and they very rarely see any difference vs. the buds growing that way. If selling to hard bud biased users, consider compressing the buds before they fully dry.
Regarding lack of hardness, being airy = LARF, I think most use the the term 'hard buds' to refer to fully mature buds (not lower or otherwise less mature buds), which constitute the great majority of buds. Many, if not most, growers clean up their plants, remove any developing LARF, and simply don't have any at harvest time.
