We have developed a novel multicellular aggregate (spheroid) formation device that utilizes a maskless grey-scale photolithography. The device was capable of producing hundreds of aggregates rapidly at a time and regulating the diameter of aggregates with complex design. The cellular aggregates have a micro-pore to supply the growth factor and to expel the waste product. As a result, the cellular aggregates enable long-term culture. In addition we can use micro-pore as continuous channel and insert vascular system and nerve system into assembled tissue.