First, thanks all for informations we can find here. Greetings to Pacificmeister for his stl release. I was checking/dreaming on your videos, i was so happy when this website has been created.
Then, here is where i am. I used 20x20 and 20x40mm aluminium profiled to try to get something the cheaper possible (at least for mast and wings).
Sadly, i am not able to 3d design more than with tinkercad, but this make the job for my needs.
Here is the thingiverse link if anybody wants : https://www.thingiverse.com/thing:2633404
Pacificmeister, i tinkercad your mast mount to be screwed on aluminium profile, i any problem for you, i will remove them.
A lot of more work to do, but this is clearly one of the most brilliant diy project i ever seen. Definitely felt in love.