This is a remix of @ulitiy's nice floater for the ultrasonic mist maker:

https://www.thingiverse.com/thing:3900020

This thing floats on packaging foam, rather than on infill air pockets that are rather difficult to print watertight.

OpenSCAD file is included.

Print instructions

I printed this with PETG on the textured PEI sheet, and used “Archimedean Chords” as the bottom infill pattern.

I used soft packaging foam, cut it roughly to shape, and squeezed it into the floater. No glue necessary. I am also using this splash guard:

https://www.prusaprinters.org/prints/20578

The splash guard fits both the original design as well as this remix.