## 2 Manufacturing Processes of Musical Instruments Made of Composites and Alternative Materials
### Experimental and Numerical Methods for Musical Instrument Vibroacoustic Studies
#### 3.1.2 Vibro-Acoustic Assessments of 3D-printed Musical Instruments
Titanium possesses valuable properties that allow the creation of surfaces with desirable characteristics. After selecting the optimal lattice pattern, a titanium flute was printed, exhibiting strength, high biocompatibility, and a long lifetime. Following manufacturing, the titanium flute was compared to the initial polymer analogue and a traditionally manufactured titanium flute. Studio recording tests revealed that the sound of the 3D-printed titanium flute is significantly richer than the polymer analogue. This improvement was attributed to the material's lower absorption of sound waves. [PERSON] and [PERSON] [41] developed usable clarinet mouthpieces by recreating them from surviving technical drawings, like those found in the Boosey & Hawkes Archive, using 3D printing. The research in the field extends to include traditional and even lost musical instruments, either replicated based on descriptions or existing parts. [PERSON] and [PERSON] [37; 43] focused on reconstructing the cornett, a Renaissance wind instrument that fell out of fashion centuries ago, becoming a museum artifact. Experiments successfully aimed at 3D printing replicas of the cornett, primarily utilizing SLS technology with some minor inclusions of SLA and FDM. In [43], in addition to the cornett, they also designed and successfully developed the shakuhachi, a traditional Japanese bamboo flute, and the ukulele, a small four-string guitar, a traditional Hawaiian musical instrument. The same study addressed the design of Fagottini and Tenoroons, the smaller members of the Renaissance bassoon/curtal family. Due to the rarity of playable small bassoons, the 3D-printed Fagottini and Tenoroons were successfully compared to their traditional counterparts and were used in normal concerts. [PERSON] et al. [45] studied experimentally and numerically the acoustical behavior of Kefalonian traditional instruments made from various materials and several anakari instruments were designed and manufactured traditionally from two wood types and from PLA by 3D printing. The 3D-printed instruments were compared to their traditional counterparts, and acoustic measurements and simulations, presented in Figure 14, demonstrated that the PLA 3D-printed anakari had significant differences in the produced sound compared to its replica made of eucalyptus, due to variations in the mechanical properties of the materials chosen. Figure 13: Final design of an ODD Guitar body using an internal wooden core. Used with permission of [Emerald Publishing Limited], from [5]; permission conveyed through Copyright Clearance Center, Inc.  
3D printing empowers the creation of wonderfully peculiar existing instruments or entirely new musical wonders, like the innovative slide pipes [43]. These whistle-like instruments produce diverse notes by manipulating their resonance length through a push/pull slide and were successfully brought to life through 3D printing, captivating audiences in various concerts. Figure 15 demonstrates musicians performing with slide pipes. 3D printing is on the brink of revolutionizing the musical industry by simplifying the design and creation of relatively affordable musical instruments or components. It opens the possibility of easily creating prototypes or previously nonexistent musical instruments and reproducing lost or discontinued musical treasures. Nevertheless, while 3D printing offers notable advantages, limitations such as the availability of materials and the durability of printed components, in relation to the chosen additive printing technology and design, continue to place this technique at a relative disadvantage compared to subtractive manufacturing methods [84]. PLA and PET may not be as durable as some traditional instrument materials, especially for high-stress applications, while UV-sensitive photopolymer powder may be prone to degradation over time when exposed to sunlight [85]. Figure 14: (**A**) An anakari made from eucalyptus wood, (**B**) a 3D-printed PLA anakari and (**C**) natural frequencies in anakari.