I use the masa recipe in the forum thread, and if you use some sort of spoon and force it down into water bottles and then plug them with some sponge you cut up, you can get the flies out easier than you can with the huge 32 ounce cup lids. Only problem is it takes a while to force the stuff down into the water bottle to make it fall and pile up in the bottom and you lose some on the inside top edges of the bottle as it smears there and the remnant dries out there. What is really fun is you get to pick which color you want your medium to be, as you add the food coloring drops as suggested in the thread. I got a 4 pack of food coloring bottles and it came with red, green, yellow, and blue coloring bottles, and the back of the package tells me how to make certain colors. For instance, I made two cultures a couple of days ago a Grape color by mixing blue and red food coloring evenly. I make sure I don't use too many drops of coloring as the thread says if you use too much, the flies don't like it as much.