[Eliot Ness]

   
Attached is a picture of my Crown radio.

As I suspected any information on the Custom Built Radio Company is pretty sparse.  Combing through some of the Floyd Paul archives he lists Custom Built as one of the minor players in the LA radio scene, probably because they weren't around very long.  In a list of manufacturers he lists a Nick Hiriart (possibly the owner) and an estimated start date of July/August 1931 with no date of when they ceased to exist.  He does mention the lifetime for some companies was a matter of weeks or a few months.

I did find one ad for one of their radios in the June 1931 issue of Western Music and Trades on page 17:

https://worldradiohistory.com/Western_Mu...Trades.htm

If you're interested in the Los Angeles early radio scene you should buy Floyd Paul's books on the subject:

http://www.antiqueradios.org/radio_books.html

There is a tad more info on Custom in supplement #2 of the above.