The treatment of obesity based only on lifestyle changes has been shown ineffectiveness in a long-term period. The development of more definitive and non-invasive therapies has been the subject of study. In this paper, a magnetically driven ingestible capsule with the capacity to inflate a gastric balloon is devised, simulated, and fabricated. The balloon is inflated to a volume of 150 ml using an acid-base reaction between citric acid and potassium bicarbonate. Finite element method simulations were performed to study the interaction between the permanent external magnet and the ingestible capsule and confirm the magnetic activation mechanism. A fabrication process was proposed to manufacture a polydimethylsiloxane (PDMS) balloon in a simple, functional, and reproducible way. The two layers and 1:8 ratio balloons are the most cost-effective without compromising their mechanical properties. The capsule body parts manufactured by a three-dimensional (3D) printing process -Digital Light Processing (DLP) showed high accuracy and excellent resolution. This study demonstrated that the proposed ingestible capsule would successfully inflate the gastric balloon to treat obesity.