Recommended to me by a dental hygienist many years ago, just run one of these over your tongue to scrape away bacteria that lead to bad breath.  (Don't forget to brush and floss too).

Only takes 34 minutes to print at 0.2mm layer height and default MK2s profile.

Designed in FreeCAD.

Printed with GreenGate3D recycled PETG filament.  Supports were not needed.

After use, be sure to keep this clean too, since you don't want any bacterial growing on it either.