It's just a little gadget called a "Cartesian diver" or "Cartesian devil", "Wasserteufel" in german and "Ludion" in french.
Print settings :
° without support
° layer height : 0.2 mm
° infill 100% or at least 80%
° Filament : PLA works well
A presentation video in french :
On youtube : https://www.youtube.com/watch?v=GaolH0erl88
On my Web site : https://www.juggling.ch/gisin/impression3d/freecad/fc_ref_videos.html
On my page about FreeCAD, I made some videos (in french) and linked many videos in french, english and a few in german.
The author hasn't provided the model origin yet.