Miele TwinDos is a nice system to automatically dose detergent when washing.

When you want to use your own detergent, refill containers are available.

This funnel enables you to reuse your empty/used containers.

The funnel activated the lock in the container, align the hole in the funnel with the opening in the opening. The rail in the side of the funnel lets the air out more easily.

Printable in most stiff materials, though PETG will ensure better resistance against water and detergent than PLA.

If you have any comments, please let me know.