Abstract: Support members are mounted to move between two separations, respectively less than and greater than the open end of a two-panel cover otherwise seamed together around its edges. Flaps sized to define a desired closure hemm can be in-turned manually along short opposed portions of the panel ends and then positioned over the lesser spaced support members to mount the cover thereon. The support members when at the greater separation will tension the open panel edges and extend the flaps accurately in-folded between the support members. The support members can have a first size defining a large edge opening for receiving a nozzle suited for blowing unwanted materials from between the flaps, and a smaller size for minimally gapping the flaps. A sewing machine can then automatically stitch through the panels and hidden flaps, for closing the cover end edge. Clamps can grip spaced cover locations for added cover support.