Our cat spills a lot water with this fountain, she puts her paws in the gap and lift the fountain, so I made this simple cover, you just push it on and it stays there. It is harder to lift up the fountain for us, but we don't have wet floor anymore.
Printed standing up, but if you have adhesion problems with narrow objects you can print it on it's back and use support for the small opening.
In the print picture you see the name of our cat but the one I uploaded is blank.
Cat_Mate_Front_Gap_Cover.stl | 32.4KB |