It is not always possible to have access to commercial experimental kits in order to impart knowledge to a class or perform an outreach presentation, and this often happens because of the lack of funding in schools and universities. We aimed to create an outreach demonstration using only recyclable materials and reusing old CDs or DVDs, so that everyone can use it. In this work, we present the outreach activity "Homemade spectrometer using a CD/DVD", which won the first place in the Optics Outreach games 2017 in San Diego. This spectrometer can be built with a CD or DVD and a template that can be acquired for free by emailing the University of Exeter Optics and Photonics Society (EUOPS), or can be collected in our outreach activities. We have tested this outreach demonstration in several events during 2017 and 2018 with a very positive feedback. Teachers and students within UK, USA, Mexico and Chile have required the activity worksheet in order to replicate the demonstration at their institutions.