Abstract: Additive-polymer precursor materials for filaments (e.g., for three-dimensional (3D) printing) are provided, as well as methods of fabricating and using the same. One or more two-dimensional (2D) additive materials (e.g., nano materials, such as nanosheets) can be mixed with a polymer base to give an additive-polymer precursor composite material. The additive material can be dissolved in a first solvent to give an additive solution, and the polymer can be dissolved in a second solvent to give a polymer base. The additive solution can be mixed with the polymer base to give a mixed solution. Solvent casting can then be performed on the mixed solution to evaporate the solvent(s) and give the additive-polymer precursor composite material, which can have a layered structure.