The present disclosure concerns a digital fabricating method for constructing 3D structures, comprising the following steps: (a) precursor consist of monomers and photo-initiator is introduced into reaction cell; (b) exposing the precursor to the DLP projector for several times to gain an inhomogeneous sheet; (c) swelling the sheet in solvent to gain 3D structure. The disclosure provides a simple and easy way to produce precise 3D structure.