John, I am Delighted to Report that I can't see any Solder, What did you use??

:biggrin:
I see that some others are speculating on what you have, or have not done. I will leave that for them to Pontificate about.
Love your Concept , and No I don't think the Copper and Brass will be a problem. :good:
I love the small Tube section at the Nib end, and how it Compliments, the Tubes on the Body.
The only thing I noticed was that at the top end of the Tubes of the Body Section, there is some discolourisation of the Top of the Brass Tube, I can't tell if it is due to heat transfer, or if it is a bit of rubbish or dust.

Regardless it is Fantastic.
As I said in an earlier Post, I probably would have "Thrown it against the Wall", but not You.
Congratulations, My Friend, you have come such a Long Way in a Such a Short Time, due to your Diligence and Tenacity.
Regards and Celebrations,
Brian.