Slimline Envelope #10 Dies Build your own selection of Slimline #10 Envelopes with this mega die set! This set of 5 dies will allow you to create a variety of different styles of envelopes. First use the large rectangle die to create the envelope base, then cut two of the longer side panels and attach to either edge of the rectangle die cuts. Then choose from the selection of three smaller edged dies - a standard flap, a stitched scalloped semi-circle flap, or a bracket-style fancy flap. Glue these all together in a myriad of different ways to get the exact look you want to achieve! Completed envelope measures 9" x 4 ".