This is a filament filter made from two pieces so that it is easier to insert a sponge and replace it as needed (or add more oil) without having to print a new filter. I reverse-engineered this from the Universal Filament Filter by CreativeTools (with marginal dimensional changes) and then modified it into two interlocking components.
Print with the flat sides of both parts facing down. The pieces seem to hold together reasonably well, though I have not used this filter during printing yet. Worst case, you can wrap a short length of 1/2" tape around it.