A study of bubble formation, movement and distortion in viscous glass is described. A glass rod containing an irregularly shaped hole is heated to a temperature at where the glass viscosity is low enough to let the hole form a spherical bubble. Spheration occurs as the bubble moves upward in the glass rod. At the proper time, the rising bubble is decelerated and brought to a stop by increasing the glass viscosity by slowly reducing the temperature. The entrapped bubble is then cut from the glass rod and heated again, if necessary, to a lower temperature, to reduce distortion of the bubble. Conditions distorting the bubble and ways to reduce the distortion have been investigated. With the present technique, bubbles have been produced in Corning 7740 and Schott BK-7 glasses with a nominal diameter of 3 and 6 mm that have a distortion of 0.3%. Glass macro shells can be formed from the bubbles trapped in the glass by grinding the outside surface concentric with the perfectly spherical inside surface. These high quality glass shells, with a high degree of geometrical perfection, should be adequate for inertial confinement fusion targets.