This is a neat little earplug with adjustable damping that I designed. It's meant for concertgoers and musicians, and provides a relatively linear (bass to treble) dB reduction ranging from almost no damping to medium damping (that's at least how I would describe it).
Just use a standard, comfortable silicone or foam ear tip of your liking.
Adjust the sound reduction by turning the knob - I've made it relatively loose so you should be able to adjust it while it's in your ear, but that will depend on your printer as well.
I also made a small box that fits two earplugs.

Enjoy, and take good care of your ears!