Now that each design block is cut to final dimension it's time to attach fusible interfacing to aid the sewing and stabilization properties of each quilt block. Position design blocks on your interfacing yardage to have the least amount of waste, you can cut right up to the edge of each design block.
Use a hot iron with steam to adhere interfacing and refer to the interfacing directions if you have trouble. Not all screen prints are created equal, so to avoid melting the ink use a damp ironing cloth over the print when needed. Press well at this stage but there will be numerous other opportunities to ensure complete adhesion.
Once the design blocks are adequately attached, remove them from ironing surface and carefully cut apart with scissors or a rotary cutter. Press individual blocks again with steam paying special attention to adhering all edges. Complete one vertical strip at a time and lay them back out in the order of your final quilt top.