Make a killer fly trap out of a mason jar. Just print the desired size lid (for either small or large mouth jars). Put on the new lid and use a ring to secure it in place. Here is a link to the bait I use: http://goo.gl/IRqHsU It smells like death and the flies love it! Works like a champ. Make sure to put this thing 50 feet away from the area that you'd like to be fly-free. Make sure to put it in a place that gets a lot of sunlight. The heat really kicks up the stench-factor of the bait. If you are using PLA, you might want to make a small paper cone to shield it from the sun. Put a large knot in your suspension string to support it (see photos).