I am very excited to see this Prze!
What did you use to polish away the printing artefacts?
I am using several grades of sand paper.
That would also be intersting for me.
That 3D printing structurs scare me, especially on parts like motor or other delicate structures. Do you have some honest pre- and post-polishing pictures in order to see the effect? I would guess, it is highly depending on camera/light angels.
However, thank you so much for this new thread 
Rafael
The traces are barely visible, hard to photograph. But mayby here you will notice the difference between raw and polished strut. And the untreated element still not removed from the printing tree.
They are most notable in the sound you hear when polishing, clearly indicating the regular roughness of the surface.
Looks like you're off to a solid start, Przemol! I really enjoy seeing how some of you guys drill and pin more positive connection points since that's a technique with which I've experienced mixed results. I'll be paying close attention to this topic of yours since I've got a Lukgraph Halberstadt in the stash and hope to add some more of their kits soon.
Those butt joints require reinforcement, especially the control surfaces which will later be pulled by the control lines.
