I created a grid to put inside the floater of the EccoSkim skimmer from Juwel. Hopefully it will prevent any shrimps/little fish from getting inside.

I sliced it using PrusaSlicer and used the EccoSkim_grid_middle_part.stl to modify the interior of the EccoSkim_grid_full_insert.stl so the middle of the part prints with no top/bottom layers and just infill. This is in my opinion the way to go, because you can use basically any infill pattern for the insert. I had the best success with a 30% grid insert. Any higher and the skimmer wouldn't work properly anymore.

After printing you can just drop it inside the floater and maybe adjust the flow a little so the skimmer does its job.

It was designed using Fusion 360.