OC scaffold phases made via various 3D printing techniques. Some techniques, such as ME printing for thermopolymers and hydrogels, are commonly used across all phases of the OC scaffold, while other techniques, such as MEW, are commonly used only in one or two phases (cartilage and calcified cartilage). (A) Insert scale bar = 1 mm [183]. (B) Scale bar = 2 mm [113]. (C) Scale bar = 1 mm [184]. (D) Scale bar = 0.01 mm [165]. (E) [123]. (F) Scale bar = 5 mm [103]. (G) Scale bar = 2 mm [181]. (H) Scale bar = 0.5 mm [143]. (I) Scale bar = 5 mm [109]. (J) Scale bar = 2 mm, insert scale bar = 1 mm [104]. (K) Scale bar = 2 mm, insert scale bar = 1 mm [104]. (L) Scale bar = 2 mm [113]. (M) [156]. (N) Scale bar = 0.01 mm [165]. (O) [123].