Code:
every 3 seconds:
loop all players:
loop {gens.%loop-player's uuid%::*}:
if block at loop-index is air:
remove loop-index from {gens.%loop-player's uuid%::*}
else:
drop paper named "&b1 Crystal" with lore "&fCommon Banknote" at location 1 block above loop-index
stupid underdeveloped plugin