Ceramics with complex shapes are desired in many applications, including architectural design and construction, protective systems, molds for gas turbines, and biomaterials. 3D printing techniques through photopolymerization are perhaps considered the most powerful approaches for the fabrication of ceramics with complex shapes. However, these procedures are usually difficult to implement, are time-consuming, require further processing, and result in material waste. Here we report on a simple, fast, and yet powerful self-shaping procedure to make ceramics with complex shapes. The approach draws on a principle that the amount of shrinkage a ceramic undergoes during sintering is a function of the concentration of particles in the ceramic resin: the higher the concentration, the less the shrinkage. By printing components with inhomogeneous concentrations of particles, the parts with higher concentrations shrink less during sintering, resulting in well-controlled shape changes. This approach does not require extensive instrumentation and can be used for a wide range of ceramics. We then developed a material- and scale-independent mechanical model based on linear elasticity, which predicted the shape changes accurately. The model can be used as a tool to design the self-shaping experiments, potentially for a large variety of ceramics and glasses.