Arbitrary and high-precision thermal patterning has long been desired in the field of thermal functional materials. However, existing thermal patterning strategies have not been widely applied, either hampered by the difficulty in fabricating anisotropic metamaterials or limited by complex thermal manipulation. We propose an on-demand thermal patterning scheme that sandwiches geometrically engineered heating arrays between a substrate and an encapsulation layer to form composite structures and control the omnidirectional transfer of the heat flux generated by the heating arrays. These heating arrays are digitally assembled from multiple heater cells of varying widths and continuously printed using electric-field-driven 3D printing. A design strategy for thermal patterning with good uniformity within individual regions and high contrast between regions is proposed. The performance of the on-demand thermal patterning is verified via high-precision thermal printing. The proposed scheme provides a general and reproducible method for designing thermal functional materials, with potential applications in thermochromics, messaging, thermal camouflage, and illusions.