I've become obsessed with making the perfect fruit fly trap. My workplace is infested with these insidious pests. I've designed and printed several traps. This one seems to have potential. It screws onto the top of a standard bottled water or juice bottle. The grid on top allows the lure (vinegar & a couple drops of dish soap) smell to attract the fruit flies. They will perch on top curiously before eventually making their way down into the death trap. This is a work in progress.

Update: Several flies have entered the trap and can't get out, but I think my lure formula needs some tweaking.