Northwind
I have gone through my Journals and even found my school books Ahhhh
to see if I have missed something or Learnt from your description of
a by-product.
This is what I have found from my journals for what is defined as a by-product.
A product made during the manufacture of something else.
A material other than the principal product generated as a consequence of an industrial process.
A secondary metal or mineral product recovered in the milling process.
Material created incidental to a production process which can be sold for value.
Now I hope you have read this one incorrectly.
A by-product is a secondary or incidentally during production of something else. A side effect.
Then you nead to read this again as it points out to, production of something else!
Now as each process is manipulated and to form the construction of the Downtube. Then there is no by-product, nor side effect been produced from the manufacturer or manufacture of this part.
However I did find a by-product of unemployment and if you gave such invalid and incorrect advice as on a professional level/opinion this could see you swiftly out on your assssssssssssss