The Glittergun was a weapon developed by the enemies of the Cybermen during the Cyber-Wars once their vulnerability to gold had been discovered by the humans and other allies of the Vogans.
The weapon fired gold dust particles or even sometimes molten gold into the chest units of the Cyberman, plugging up their respiration system and suffocating them. (TV: Revenge of the Cybermen)
Tobias Vaughn personally designed and funded the development of the glitterguns. (PROSE: Original Sin)