This paper describes the design and the manufacturing of the 3U Cubesat URSA MAIOR (University of Rome la SApienza Micropropulsion for Attitude and In Orbit debris Removal testing), designed in collaboration between the II Faculty of Engineering of Bologna University and the Centro Ricerca Aerospaziale Sapienza (CRAS). The Cubesat is developed in the framework of the QB50 project, leaded by the Von Karman Institute For Fluid Dynamics, and will host a sensor set for atmosphere parameters analysis. Despite its small size, this Cubesat is a complete platform for space experiments, with a system for active attitude control, a redundant telecommunication system and a high efficiency power control system. This allows to perform complex experiments, in addition to the QB50 one. These include, in the same mission, the test of a micropropulsion system, in order to verify the effectiveness and the efficiency of a MEMS cold gas micro-thruster, a miniaturized three axis attitude control system developed in house, and a space debris remediation technique and the related systems, based on a bi-component polyurethanic foam specifically developed for operation in space. In addition, the Cubesat structure, realized using a polymeric material and the technique of rapid prototyping, thanks to the equipment provided by the V-Lab of the II Faculty of Engineering of University of Bologna, is a technological experiment in itself. The satellite architecture, the subsystems development, assembly and ground testing is described.©2012 by the International Astronautical Federation.