The last few details
Taking apart your muslin
When the garment is completely fitted, let the person out by undoing the pinned opening. This should leave enough room to wriggle out. Mark along the seam lines with a marker, following either the pins, or the sewn seams. At various places on the seams mark 'notches', small lines perpendicular to the seam line so you can match your pieces later. You may wish to use different numbers of notches together to indicate different seams. Label all the pieces before you take them apart, so that you know how they relate to one another (e.g. CF, SF1, SF2, etc.). It is also a good idea to put your name and the date on your mock up, to avoid confusion. Take apart the pieces and trim off the excess fabric, leaving only your 1/2" or 5/8" seam allowances. You may also wish to mark a "grain line" on your fabric, indicating where the 'straight of grain' is so that it can be reproduced on the final garment.The last few details
When all of the basting, fitting , labeling, and trimming is completed, pull apart the mockup pieces. This is your pattern, from which a garment may be cut from the desired, prepared fabric. The first time you make the garment, select a fabric that does not have an obvious directional nap (like a velvet). Fabrics with a nap should be cut with care, so that all the front pieces will have the nap running in the same direction, the back pieces in the other. Or make two (one for a friend!) and lay each persons dress consistently in the same direction.
The garment can be sewn in the same sequence as the mockup, beginning with the front side gores, then the back side gores, then the side seams. But because of the bulk of the dress, it is easier to sew the neck and garment opening facings, as well as their buttons and buttonholes, before you attach the side panels. It is also easier to sew the buttons and button holes onto the sleeves before attaching the sleeves to the dress. For information on the materials and sewing techniques used on these garments, please see my other essay, "14th Century Materials and Sewing Techniques".