Summary

This is my new version of my fleece filter V2.1:
https://www.thingiverse.com/thing:3733938

The inlay is more robust and has a snap-in mechanism now.
The both outside parts must be glued together with super glue.
I've created two parts to be able to print it with my prusa i3.
The water slide and filter holder just matches the dimensions of my filter tank of course, but could be used as a proposal. Works perfectly this way since two weeks.
The new version catches more dirt (detritus), maybe due to the water slide...

Just another hint (maybe optional): I carefully treated the areas where the fleece moves with sandpaper to avoid the fleece getting stuck there.
Finally, I treated the areas with a flame.