Schecter Guitars just released a new instrument called the Machine Gun Kelly Razor Blade and it's being universally ripped online ... with tons of folks saying it promotes, glorifies and advocates cutting.

The issue ... razor blades are often used by people who cut themselves on purpose -- and not just that, but there's a stereotype about fans of pop-punk/emo rock engaging in self-harm ... which only heightens this convo, considering Kelly's affiliation with the genres.

In light of all that ... the company's Instagram post announcing the new MGK signature guitar is being bombarded with negative comments -- with folks slamming the guitar as Schecter's worst offering ever.

In introducing the guitar at a recent gig, Machine Gun Kelly explained it's "kind of an ode to Tickets To My Downfall, the line on title track and also an ode to my 20s and all the crazy times that I had." Unfortunately, folks are calling this out as promoting cutting, even if indirectly.

MGK's heard all the noise, and now he's singing a different tune ... saying, "I'll never explain my art because art is conversational and always up for interpretation, but I will say, most of you constantly interpret it wrong."

Seems like the early negative feedback may be affecting the sale price ... Schecter originally listed the guitar for $2,169 but the price tag has already been slashed to $1,499 ... a $700 reduction.