Upcycle your used fabric-softener sheets from the dryer to your Neato Robotics vacuum cleaner! I can't speak for the comparative efficiency of this design versus the real thing from Neato, certainly it's not HEPA standard. However, it only costs about a meter of filament plus something you would otherwise throw in the trash. Therefore I dub it "cHEaPA!" (The alternate file, neato_filter_w-tabs.stl is an attempt to add locking tabs, but I haven't successfully printed it yet.)Print the design, then fold it in half with a used dryer sheet between. Trim the dryer sheet around the edges and glue the frame together. (I'm pondering on a way to make this snap together, but haven't come up with anything so far. Certainly I could print it on a raft to allow tabs on the mating faces, but I hate printing on a raft... .)