Equal Temperament is an abstraction - different instruments will have an entire discipline of temperament. One of the more complex suites of temperament regimes are the temperament regimes used on pedal steel.
Getting a steel to "do" ET is actually an achievable engineering problem, but players may prefer the sound of something more akin to Just intonation and older guitars may not be able to be in ET. Guitars with all the parts to achieve ET are relatively obscure.
Getting a steel to "do" ET is actually an achievable engineering problem, but players may prefer the sound of something more akin to Just intonation and older guitars may not be able to be in ET. Guitars with all the parts to achieve ET are relatively obscure.