New Scale

Not sure what you mean new scale based on a piece.
Theorists think that scales evolved largely because 
of the physics of the instruments making them, or
to fix some existing tuning problem, or in some cases
for a particular musical purpose (eg: whole-tone scales
for impressionist music, underwater scenes, dream 
sequences, etc.).

Composers often decide to write a piece in a particular
scale.  Again, I'm not sure what devising a scale based
on a piece.  Maybe you're talking about a "Pitch Class"
or "Pitch Set"  That's got some good history and application
in composition.