This study presents a fabrication process via experimental observations for curved porous multilayer structures with a single-step, co-sintering operation. Active monitoring of the shrinkage behavior of each porous layer during the co-sintering process leads to minimize mismatched stresses along with avoidance of severe warping and cracking. During co-sintering, in-plane stresses are developed in each layer due to differing shrinkage behaviors between layers. Analysis of curvature evolution using in situ monitoring of the structure was performed in the design of a curved multilayer structure via the co-sintering process. Materials used are NiO/CGO for anode; CGO for electrolyte; and LSCF for cathode. These materials are tape casted with 20 m thickness and stacked to form bi- and triple-layer structures by hot-pressing. Bilayers, consisting of NiO/CGO-CGO and CGO-LSCF, were co-sintered up to 1200 degrees C. The maximum sintering mismatched stress was calculated at the interface of bilayer structure. In situ observation, to monitor the shrinkage of each material and the curvature evolution of the bi- and triple-layer structures, was performed using a long focus microscope (Infinity K-2). Thereby, viscosity, shrinkage rate of each material, and curvature rate were calculated to determine the mismatched stresses. The monitored results contributed to development of novel design of curved 3D multilayer structures during co-sintering.