Cosmic Gun, the device art, is an amateur, low-cost astronomy project that enables the general public to be connected momentarily with cosmic rays coming from outside the Solar System. The metaphor of contacting cosmic rays is far more than literally interpreted, the poetics of this project built upon the notion that ‘The Solar System belongs to everyone on this planet, any authorities aim for taking this fundamental rights away is brutally attacking our beliefs on human rights as a global citizen.’ The workshop will introduce different cosmic rays detectors inventions around the globe and hands-on technical skills on building DIY cosmic rays detectors. At the end of the workshop, participants will finish building their own custom made cosmic rays detectors. This workshop project is supported by the Arts Development Fund of the Home Affairs Bureau, the Government of the Hong Kong Special Administrative Region. Cosmic Gun was originally commissioned by New Vision Arts Festival 2014, Leisure and Cultural Services Department, the Government of the Hong Kong Special Administrative Region.