I'm dipping briefly into costumes now, in time for the rennaissance fair season in the U.S. I'll get back to everyday wear (tops and dresses) next week after I've had time to do some up and double-check my instructions.
The cloak is the easiest, most ridiculously overpriced costume element you can find. The half circle cloak is the easiest cloak to make, and gives you a very full, swishy circular look with a front you can pull around and close in front.
If you’re under 5’ tall you can use 45” wide fabric for a basic circle cloak. 5’ to probably about 6’4” you can use 60” fabric. Anyone taller than that can try to hunt down wider fabric (shoot for a width about from your shoulder to your ankle) or deal with the fact that you will have seams in your cloak.
Cloaks need a LOT of fabric for that full swishy look. You need a piece of fabric twice as long as it is wide for the main cloak, plus some for the hood. If you’re using 45” fabric, get at least 8 yards (might be a good idea to get 8 1/2 so that you have a safety margin). If you’re using 60” fabric you’ll need 10.5 yards (or 11 with safety margin). This also means that you’ll need a big flat area to work on. I’ve found it’s easiest to vaccuum the floor, lock the cat in the bedroom and just spread the fabric out on the carpet. (Trust me on locking the cat up, they’re fascinated and tend to sprawl on the fabric just when you need to move it.)
Wash and dry the fabric (if washable!) before working with it, to prevent shrinkage. Cut the fabric down to double the width (7.5 yards for 45” fabric, 10 yards for 60” fabric). The extra will be used later for the hood. Iron out any creases or wrinkles.
Fold the entire piece of fabric in half to create a large square. Select one of the corners on the fold. Take a long piece of string and tie a piece of chalk or a pencil to one end. Secure the other end at the corner of the fabric (I safety-pin it to the carpet, but if you have someone to help you just have them hold the string down at the corner.) Make sure that when you hold the chalk with the string taut the chalk just reaches the other corner of the fabric on the same edge. You’re essentially creating a giant compass. Keeping the string taut, trace a line from one corner to the next, creating an arc.
Shorten the string to 6” and make a smaller arc near the corner. This will be the opening for the neck. (Note: if you have a thick neck or broad shoulders you may want to make this 8”)
Cut along both these lines. Open up the piece and hem the bottom and side edges by ½”. If you want a cleaner edge, consider folding the fabric up ¼”, then folding over again another ¼” to fold the raw edge under. Pin this, iron to crease and stitch.
If you made the neck opening 6”, you’ll want 19” of fabric for the hood. If you made it 8”, you’ll want 26” of fabric. Use whatever width your fabric is for the width. Cut the piece and fold it in half with the right side (the side you want to show) together (or use a french seam as explained in the next paragraph). Stitch one long open side (red line) and hem the other (black line). When hemming the open end, hide the raw edge by folding under ¼”, then folding ¼” over that. Iron and pin before stitching for more even results.
Since the seam at the back of the hood (red line) will be visible with the hood down, you may want to do what’s called a french seam. Put the fabric WRONG side together, so the part you want on the inside when wearing the cloak is on the inside. Stitch a ¼ inch seam along the long end. Snip any stray threads and make sure the fabric is cut as close to the stitches as possible without them actually coming undone. Fold the hood inside out so that the seam you just made is on the inside. Along the same seam, use basting stitches (long, loose stitches) a little over ¼” from the edge so that your original seam is tucked inside. When you turn the fabric again you should have a clean seam on one side and just a fold of fabric on the other. If you see the raw edge sticking out of your french seam, undo the basting stitches and try again a little further from the edge. Otherwise go back over your basting stitches with a straight stitch to close the seam.
Since there may be a difference between the size of the hood and the neck opening of the cloak, begin by pinning the corners together. Then find the center of each fabric and pin again, then divide each gap in half and pin again, etc. Any remaining gaps can be captured in small pleats or folds when you sew the fabric together, but pinning first will make sure that they’re even.
To make a drawstring, you can either use a ribbon, leather cord, or a piece of the same fabric as the cloak. To do the last, cut a 1 ¼ ” wide strip of the fabric. Fold each short end in ¼” and hem. Fold the strip in half lengthwise with right side folded together. Stitch all the way down to create a long tube. Attach a safety pin to one end and feed the safety pin down inside the tube. As it works it’s way along it will pull the end with it to turn the entire tube inside out. When it is inside out, iron it flat and stitch both ends to close the tube.
Attach a safety pin to one end of your drawstring. Feed it through the tube created by your french seam when you attached the hood. Push it all the way through until you can pull it out the other side. Adjust the two ends to be even, and you’re done!