Curves are very natural and organic looking, and people love to look at them. So while I love stripes and can appreciate linear lines in some designs, I always come back to the curves.
Often these curves are on flaps, which end up being a focal point of the design. Making the curves of the flap as smooth and as identical as possible is going to help tremendously with the finished look of your piece. So here are some tips geared toward getting these small curves to look great.
True your curves by trimming each side of the flap to an identical shape before you begin sewing:
If you have a particularly difficult curve and just can't seem to get it right, trace the stitching line around the curve using a scallop rule or other curved item:
After clipping or notching curves, trim away about half the allowance so there is less fabric vying for space inside the curve once the piece is right side out:
If you have a lot of layers, you probably need to grade the seam. Grading is done by trimming the layers successively shorter, but leaving enough of fabric for the stitching to have something to hold onto (about 1/8").
This photo shows a straight seam, but demonstrates the concept of grading:
The grade looks tidy in the photo, but in real life the places you trimmed might look messy and choppy. That is ok, just get rid of some bulk.
Once your piece is turned right side out and ready for the final pressing, examine the seam around the curve.
Sometimes even though you pushed the seams out neatly from inside, once you remove whatever implement used to push the seam out, it will collapse back inward. For these sections you can massage the seam out by rolling it between your fingers until the fabric falls into place.
If the finger massage method doesn't push out all the caved in areas, then use a needle to carefully pull the fabric up.
Once you've got the curve looking neat, press the piece and then let it cool so the fabric sets in place.