I got this idea from my favorite yoga pants pattern Kwik Sew 3115. This pant is so quick and easy to make but since I am a lazy sewer I decided to convert it to a no side seam pattern to make it even quicker!
This is how I did it.
1. Since this was a flared leg pattern I first straightened the legs. Measured and drew a straight line from the point where the flare started. Make sure that you keep it parallel to the grainline. Grainline is very important in this. Extend it fully
2. When both front and back legs were straightened, I placed them side by side with the outside seams together. In this the crotch curve of both the pattern pieces should be facing outwards.
3. Overlap the outside seams a little. If the edges are not straight dont worry just tape them together. If the pattern has a hip curve the patterns will not meet at the top. Dont worry leave it like that.
4. so now we have taped the two pattern pieces at the outside seams and if there is a hip curve there is a gap on top. Put a piece of tissue paper under that gap and tape it. What you have now is a curved DART! So when you stitch it you'll get that nice hip curve without a seam on the sides!
5. Last step is Trueing the hemline if its distorted and marking the grainline again.
There you have it... Just one pattern piece! I did this a while ago but only yesterday I tested it and wow! I was able to make these pants in less than an hour including the cutting time! You gotta love that.