When flameworking, eyewear can protect one's vision by shielding from projectiles of thermally shocked glass. More uniquely, didymium lenses filter out the wavelength of light in the sodium flare of torched molten glass, thus altering the wearer's perception of certain colors. When people try my safety glasses on at demos, they usually think this is really cool.
I popped the plastic lenses out of my contemporary safety glasses and used a jeweler's saw to cut the lenses to fit these vintage frames. They're not totally finished yet, but it makes me really happy to customize my safety gear like this.