Material extrusion for ceramic additive manufacturing with polymer-free ceramic precursor binder

•Materials extrusion, direct ink writing (DIW) 3D printing, is the most promising and practical additive manufacturing for dense and elaborated ceramics.•The sophisticated design of sol-gel Al2O3 feedstock and 3D printing process optimization for material extrusion-based on physicochemical properties enables the manufacturing of diverse shaped Al2O3 objects.•The 3D printed Al2O3 from high solid loading (50 vol%) in sol-gel Al2O3 feedstock demonstrated comparable hardness and flexural strength with commercial Al2O3.