After reading all the posts, I'm in agreement with some, disagree with others on certain points, and laughed my arse off at some of the comments.
Hope I'm not stirring up the sh*t-storm again but have a question regarding drivetrains & suspensions. Let's say we go by the definition that a "custom" car is one that the body, frame, interior, everything on it was designed, fabbed and built by the same person or for said person. But then the person puts in a 572 crate motor, 4L80E or Tremec manual trans, backed up by a Ford 9", GM 12 bolt, Dana 60 whatever rear-end. Is the vehicle still custom? Since the drivetrain pieces were / are available in a mass-produced manner, does this strip the car of being "custom". Also, what of the suspension pieces? If the person uses a Mustang II front-end, a GM Short/Long A-Arm, Mopar torsion bar, whatever, along with a 4-link, leaf-springs, or whatever, does the car lose its "custom" status? Tires? Seats, i.e. frames, brackets. Lights? The lists goes on and on.
And along with Foose, Troy, Coddington (RIP), they do / did the same thing. With Chip and the Boydster, is that a "custom" car or a "modified" copy? Chicane, is that a "custom", "customized" or "modified" Chevy Biscayne? When the Aluma-tub was designed, fabbed & built, a mass-produced LS-motor was dropped in it, is it not "custom" anymore.
My point of going on is, if only going by the "everything has to be one-off, non-mass produced, only spec'd & used by the individual who came up with it, idea not copied from someone else..." definition, dictionaries, scholars, everything and body else be damned, then NOTHING can ever truly be "custom".
How about we just use "customized" or "modified"?