A simple low cost building drum, free of axially movable parts for building tires and cylindrical articles having inextensible beads of given diameter therein but spaced axially any selected distance apart, has a single axially and circumferentially continuous radial expandable membrane overlying a thick-walled cylinder of deformable rubbery material the full axial length of which is expandable radially to wrap the membrane against beads placed about the drum and to divide the membrane into a non-inflatable center section and two inflatable end sections each axially outboard of a respective bead. The thick-walled cylinder is expanded radially by inflating an axially extending cylindrical sleeve within control members in the form of four semi-cylindrical strips which prevent bulging outward of the central portion of the thick-walled cylinder and which engage cylindrical flanges of a pair of end rings spaced along the drum's center shaft.