kitchen ceiling strip

During the renovation of our house I put some ceiling strip in the corner put it's very difficult to miter them in the right angle. Specially if the corners aren't the 90 degress. Maybe I'm too stupid to cut them in the right angle.

We use these similar strips from the hardare store:
https://www.amazon.de/deckenabschlussleisten-Baumarkt/s?ie=UTF8&language=en_GB&page=1&rh=n%3A80084031%2Ck%3Adeckenabschlussleisten

So that's the perfect job for an 3D printer.

As you see on the picture I'm