Fig. 4: Automated free-form 3D printing of springs using distinct FP inks which achieve identical geometry and spring constants despite different frontal polymerization rates.

a Schematic of 3D-printed spring, highlighting the linear section and the freeform unsupported section. b Average front velocities and corresponding images of 3D-printed spirals using DCPD [150 ppm] and DCPD-co-iPrSi8 inks. c Compression testing results, showing that both printed spirals achieve the same spring constant despite differences in material composition.