Sons of industry?

[JimL]

As we all know the members of the "Mighty Handful" followed other professions outside music.

I'm not so sure about all of them.  Borodin was a chemist and RK a Naval officer, but Mussorgsky?  Other than a soldier, he was pretty much a full-time drunk after he left the Preobrazhensky regiment, Cui was a critic and writer, but that isn't too far from being a musician (since he was, I believe a music critic) and I think Balakirev was pretty much a full-time musician, although he spent more time doing field work in folk music and teaching than actual composition.

[febnyc]

Jean Cras was the son of a French Naval Officer and he, himself, rose to the rank of Rear Admiral.  He also wrote some lovely music along the way.

[alberto]

According to Wikipedia (I have read the tale elsewhere and before; is it on the ground of Antheil autobiography "Bad Boy of Music"?) Antheil, before dedicating himself to patents, "considered himself an expert on female endocrinology".
The glamorous Austrian actress Hedy Lamarr at first "sought Antheil's advice about how she might enhance her upper torso".
Cui was an army officer and a military fortifications teacher.
Balakirev was a full time musician, but for a few years (circa 1872-1876) he was a railways clerk.
Berwald managed an orthopedic clinic in Berlin (inventing orthopedic devices);in later years, in Sweden, he ran a glass workshop.
Chabrier was for many years a civil servant (Justice Ministry); he resigned just in the final years of his not long life.
Roussel served some years in the military fleet. 

[Dundonnell]

Of Swedish composers: Natanael Berg(1878-1957) was a vet. He served in the Swedish Army and rose to be veterinarian in charge of the King of Sweden's horses.

Kurt Atterberg(1887-1974) worked at the Royal Patent Office in Stockholm for 56 years, only retiring, after thirty-one years as head of a division of the office, in 1968 at the age of 81