Fig. 2

3D printed preforms: a (I) Square-base 3D printed polycarbonate preform. a (II) Drawing cone. a (III) Resulting polycarbonate fiber after thermal draw. a (IV) Fiber cross section after the draw process, with no layer delamination. The cross section is rectangular due to non-isotropic porosity of the infill pattern (scale bar 200 μm). a (V) Drawn fiber before annealing. a (VI) Drawn fiber after annealing with apparent optical transparency. b CAD models of Glass preforms, successfully realized in soda-lime glass with high-precision extrusion-based 3D printing. b (I) Structure mimics blue tarantula hair. b (II) Preform model with non-equilibrium cross-sectional geometry (scale bar 1 cm). c (I) Square-shaped glass samples with increasing glass infill (from left to right), printed with SLA technique. c (II) Detail of glass sample before baking (left) and during baking (right). In the latter, it is possible to see the black coloration resulting from the carbonized residues of resin, while the tip presents white coloration after these residues are ashed out. c (III) Picture under microscope of the ashed-out section (scale bar 200 μm), where the white coloration is a result of the natural color of the compacted milled fibers in an interconnected porous structure. Moreover, the nominal width of the glass fiber, indicated in the image by d, correlates to the expected values of 16 μm (#38 Fiber Glast). c (IV) A plot of the printed glass preforms densities (ρ) as function of the volume fraction of glass fibers mixed with resin, along with the average density of the print material