Exemplary occlusion and molding devices and methods involve the use of an expandable balloon. Methods of sealing an aortic side branch in a patient can include advancing an occlusion device within the aorta, positioning a toroidal balloon of the occlusion device adjacent to the aortic side branch, and inflating the balloon to prevent peripheral blood flow from the aorta into the aortic side branch while a central aperture of the balloon allows descending aortic blood flow therethrough. Methods of molding a stent against an interior surface of a vessel of a patient can include advancing a molding device within the vessel, positioning a toroidal balloon of the molding device at least partially withing the stent, and inflating the balloon to exert force to the stent thus dilating the stent and molding it to the interior of the vessel while a central aperture of the balloon allows blood flow therethrough.