@ Corchet
use this free cool one for image: https://imgbox.com existing eternity and cool system of management!
And this free one for files till 20 Gigas each file :) http://www.wesendit.com existing 7 days (in free mode)

Another method...(in French here with some little other tricks! ;) https://moiscript.weebly.com/trucs-astuces.html

An arc circle and Bool Diff materialize the cutting line.


Selection of the 4 sides for the Inset function


Boolean Union if needed


Selecting an Edge and Box Selection for Fillets