TR Balloon technique allows you to insert 3D inflations into structured garment designs, without the use of gathers or tucks.
Here just as you would when drafting a skirt block that you want to add flare to, you will need to draft two triangular volumes to add to your pattern.
Cut out two fan shaped pattern pieces, which you will add to the area of your block you wish to inflate. Divide the area to be "blown up" into two, cut into them and then insert your identical fan shaped pieces. Now re-position this ballooned section into the selected area of your block by pinning and then sewing them into place. Finish your block seams and edges, then turn out to right side to see the effect of the inserted inflation.
You can draw new TR style lines at a slanted angle through the wavy inflated section. I recommend drawing your style lines in a perpendicular direction to that of the balloon's folds, so as to not interfere with the overall visual effect.
For further informations,
Visit website "www.trpattern.com"