One typical example of photopolymerization-based 3D printing is stereolithography (SLA). SLA uses a laser to selectively cure the photopolymer from top to bottom, layer by layer while lowering the platform inside the liquid resin tank. This technology further results in biocompatible products using biocompatible or biodegradable photopolymers such as polyvinyl alcohol (PVA), polyethylene glycol (PEG), Poly(ethylene glycol) diacrylate (PEGDA), and so on. 7 To look further into the publication trend based on four major 3D printing technologies-powder bed fusion, jetting, extrusion, and photopolymerization, the annual publication counts for the technologies from 2001 to 2021 are shown in Figure . Extrusion grows dramatically after 2014 and becomes the mainstream among these four methods in 2021 (Extrusion: 48.4%; Powder bed fusion: 27.4%; Photopolymerization: 19.5%; Jetting: 4.7%). As the timeline indicates, powder bed fusion and extrusion are two major techniques (34.6% and 37.9%, respectively).