Update: I edited the bottom of the diffuser so that the slant coveres more of the base. This allows it to be printed upside down without any supports needed. 

This is an essential aquarium tool if you're old school like me and still do water changes using buckets. 

This water diffuser allows you to pour water from your bucket into your tank without disturbing the substrate. It hangs on the inside rim of your aquarium (works on rimless and rimmed tanks) and moves the water to the side rather than down. Just hook it on, pour the water in, and then set it aside until your next water change.