- Arium. Aristides Instruments. "Arium is a material developed by a team of Dutch engineers and acoustic scientists in collaboration with the Technical University of Delft, The Netherlands. Its unique cell structure is responsible for the unprecedented quality of sustain and resonance of Aristides guitars. ... You can see "Arium" as a mixture of resins and particles that together creates millions of tiny sound chambers that can resonate freely in all three dimensions. ..."