Let me show you how to make your own caftan, and you will not need a pattern.
Step 1: Measuring and Cutting
Fabric, at least 1/3 yard more than is needed for the main body of the caftan (mine was a light weight denim with the stripes woven in. I found it in my fabric stash.) Note: satin has wonderful drape.
Cloth tape measure
Sewing machine (although can be tediously stitched by hand)
Wash and iron the fabric.
I folded the fabric in half lengthwise and held it up to see if it would fall long enough. I held the folded edge on my shoulder ,and the fabric fell to about mid-thigh. I wanted a longer, but the fabric was wider than I needed, and I used some of the excess to lengthen the caftan.
Then I measured for the width of the entire caftan. I took my cloth tape measure and held the zero against my spine and measured to my elbow. This was 18 1/2 inches. To this measurement, I added 1 1/2 inches for hemming.
If the fabric you plan to use is less than 45 inches wide, you may need to add band of fabric to each selvage edge. My fabric was 60 inches wide; I had to cut off the selvage edges (and used them to lengthen the caftan and for the neck facing.)
I folded the fabric in half lengthwise and then in half again across the width. I measured 20 inches from the center width, and, lucky me, I found a stripe line there. I cut straight along the stripe line through all four layers of fabric.
Step 2: Adding Length (may Be Skipped If You Have More Than Enough Fabric)
I seamed each with a 5/8 inch seam. Again, there was a stripe to follow.
I ironed the seam open.
If I had had my pinking shears with me, I would have pinked the seam allowance so that fraying will be kept to a minimum. (I did that later.)
Step 3: Finishing the Edges (Honestly, This Is a Good Time to Do It)
I did not hem the bottom edge because that edge is the selvage of the fabric. You will probably have to hem. You can even round off where the side will connect to the bottom. Your choice; it is your caftan.
Step 4: Neck Facing
In the diagram, The "T" cutting line is in red. The top of the "T" is about 9 inches, and the base is about the same, but can be longer.
The diagram shows the stitching line in green. I sewed this line. I re-enforced every corner. The "T" will be cut right up to the stitching lines.
I cut along the cutting line.
I clipped the curves to the stitching. On the corners that will form the tips in the neck opening, I cut the tips off diagonally, leaving the corner stitching intact. This will make turning those points easier.
Step 5: Finishing Neck Facing
I edge-stitched all the way around the opening. Then I pinked the edge of the facing and stitched it down. Then I turned the garment so that the right side is out.
Step 6: Side Seams
There are choices to make. One of those choices will depend on how tight you want the garment on the biggest part of you. Note: this is a caftan and should fit loosely. I sewed this garment at about 4 inches from the side edge, and I sewed it straight down. I left a wide sleeve opening (measuring one opening against the other side to get the openings even) and did not sew to the bottom edge. I left a slit in both sides.
You can sew yours with a side seam wider or narrower, or you can start with the armhole having a wide seam and sew diagonally to the side edge.
Step 7: Pretty Much Done
A nice beach cover-up. Or if you are like me, since I work on the computer in my home, something comfortable to wear so that I am not nekkid. And if the fabric is not too crinkly, I have a new nightie.