Long Gore Construction
Cut out the pieces of fabric for the tunic. Use chalk, marking pen, or straight pins to mark as instructed. I advise making a small snip on the fabric edges at these marks. Only cut a few threads ― at most half the seam allowance.
Working with the body
On the body you should mark the shoulder line from one side to the other. Now fold the fabric in half long ways, and match the edges so that the shoulder marks meet. From the shoulder line, choose one side to be the back, and the other the front. Mark a line along the fold from the shoulder line towards the back and the front. The center back line should be marked for about 4", and the front line at least 9" from the center point (where the center fold intersects the shoulder line).
Open the fabric. Your marks should form a T shape like this:
At this point, finish the neckline. (Or at least cut out the neckline opening)Neckline Link
Constructing side panels:
Attaching Sleeves to Gores
First construct the side panels. Each panel is made from 2 gores, 1 sleeve and 1 gusset.
Lay out each panel as below.
It looks odd with the diagonal edge against the top of the sleeve, but it will hang well when constructed this way.
Sew both of the panel pieces together.
The side of this panel with the diagonal edges of the gores and the top of the sleeve will ―when the panel is complete― be sewn to the body piece of the tunic.
Finishing the panels
Take one side panel and look the sleeve, specifically at the gusset - there is a corner point. This point will need to fit into the inside corner on the other side of this sleeve. Fold the sleeve in half (inside out) and pin the corner in place. Sew from the point of the gusset down to the sleeve cuff (completing the sewing of the sleeve section.)
Now go back to the gusset point and sew from there down the side of the gores. The completed sleeve panel will look like this:
The panels can now be sewn to the body of the tunic. Match the shoulder line marks on the body to the center mark on the top of the sleeve. Note that the diagonal edge will try to stretch some as you sew. To avoid the puckering, pin in place and sew from the shoulder down to the bottom of the tunic, both front and back, on both sides. The gore IS longer than the body. Don't try to gather this material into this seam. You will trim off the extra when you're finished sewing.
The points of the gores need to be trimmed as illustrated below.
And now all that is left is to hem the sleeves and the bottom of the tunic
If you want, you may use trim or embroidery to embellish the sleeves and neckline, as desired.