Run a bead of glue along the back side of the cardboard upholstery template on one of the two unglued sides.
Fit the fabric over the edge of the template the same way you did for the first side of fabric in the previous step, making sure the fabric is folded around to the back in a way that keeps wrinkles from forming on the front side of the upholstery.
Glue the fabric edge in place. Trim it to 1/4 inch if necessary to remove some bulk.
Carefully pull the final opposite edge of the fabric taut over the upholstery foam and template. Run a bead of glue along the inside of the remaining template edge, stretch the fabric over the edge and glue it in place on the back side of the template, trimming if necessary.
Set the upholstered templates aside to dry.