A toothbrush holder with 8 4x4cm compartments printed in three parts.

• base.stl
  As the bottom edges are rounded, supports are recommended for better quality (ideally some support material with 0 support interface distance), however, it's important to add support blockers to the holes for the rubber feet insets. Can be printed with any filament, but if you want to clean it in the dishwasher, use something with higher temperature resistance.
• feet.stl
  Print 4 of them with TPU. Can be plugged into the base. The softer the TPU the better for the anti slip effect. It is not recommended to skip the feet, as they raise the base to allow air flowing into the bottom holes for ventilation of the compartments. If you don't have TPU at hand, you may still print them in PLA (or whatever) but they won't prevent the holder from slipping on smooth tiles in the bathroom and may require some sanding and/or glue to fit and hold in the holes.
• inset.stl
  So far I've only created this first variant of the inset, dividing the space equally into 4x4cm compartments. Supports for the rounded corners on the bottom are recommended.

Comment if you'd prefer a different inset.