GLASS GUITAR SLIDE SIZES

Using a pen as a guitar slide?
I got bored just recently and saw a metal pen lying around. I tried using it and a slide and it sounded allright but with alot of buzzing and uneven press because it curves in and i only used half of the pen. Im pretty sure the pen is alluminum and it was some pen with a laser for office presentations or something. Its pretty heavy for its size and i was wondering if it would damage or leave any specs of metal on my guitar. Also what is the differene between a metal and ceramic or glass slide? Do they sound the same?
It shouldn’t damage your guitar any.
I have used chrome slides, brass slides, and glass slides.
For acoustic playing I like thebrass hands down. It has the best resonance and sustain.
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