Thnx!
I didn't know what to do first.
Downloaded the 2D fillet tool but couldn't manage to get it right. It's done now!

Which one do i need?

Is there a plugin to automatically create round corners from selected lines on a flat surface? Can't find it anywhere!

Like below.. (from 1 to 2 automatically).

Exactly what I was looking for! Thank you so much. This is an enormous time-saver.

I have this tube which I want to connect to the part that is lower on the surface.
The orientation should be the same as the higher and lower part (light brown area's), facing straight outwards.

Can I do this with the follow me tool? Or should I use another method?