Use this funnel to trap all of those pesky fruit flies. Place a small amount of fruit (banana or peaches work great, or yeast, sugar and water) inside a mason jar (regular mouth size) and screw on the trap. Flies will be attracted to the fruit, climb down the funnel and into the jar. Once inside the jar the flies arent smart enough to find their way back out the funnel.
The design is threaded and seals tightly around the top of the jar so the pesky buggers can't escape.
I decided to design and print two of these to replace the homemade paper cones I was using. These are cleaner and less work. Just unscrew the lid and dump out the contents (outside/at your mother-in-law's house/wherever). The traps can be cleaned with soap and water but I wouldn't suggest putting them in the dishwasher.