How to Pin a Paradox

Sometimes I find fun where I didn't necessarily expect it.  Like learning to sew pieced curves together. 
Thanks to Mary Bajcz of Milford, Michigan--Scrap Happy Mary--I've now mastered this tricky process.  It's liberating...and rewarding.
It may not be obvious, but trust me, sewing two curved pieces together takes some skill, because when you flip the curved pieces right sides together to sew them, their shapes are then radically opposite one another: convexities on top of curves, curves on top of convexities.  It took me some practice to learn to pin these paradoxes together.
I tried to explain to my husband Joe why this process is so touchy, but he got hung up on the concept of right sides together, so I never got to explain it.
Anyway.
Mary Bajcz brought her magic to the Farmington Valley Quilters at a workshop held at Sew Inspired Quilt Shop on November 15, 2012. Through her, I mastered this technique, which is liberating--and fun--because it requires use of a rotary cutter freehand to cut cuves in blocks of fabric stacked on top of one another.  The stacked pieces are then shuffled and sewn together in random order. I started making these pieced leaves in Mary's class, and continued after I got home, until I had 20 curved leaf units. 

In the photo above, I've already sewn the 20 pieced squares, stem down, to one another in 10 pairs of 2.

Believe me when I tell you that curves end up opposite one another when you flip the pieces right sides together for sewing.

I learned that there are two important techniques required for sewing these opposing pieces together. 
One is to make hatch marks across the cut curves before flipping the pieces right sides together and pinning them for sewing.  The hatch marks below are made with disappearing ink:

When I flip these pieces, I make sure that the hatch marks are on top of one another, start pinning in those spots, then carefully pin the areas between those initial pins. 
The other important technique is to use a very narrow seam allowance.  I'm sorry the photo below is a little blurry, but you can still see what I want you to see: the size of the seam allowance.  To create a seam allowance of about 3/16ths, I'm running the right hand edge of the pinned fabric exactly along the inside of the right toe on my open toe foot.  Like this:

Mary Bajcz has more on her website, and I encourage you to go there and look at a few of the ways you can apply this artful technique.   https://sites.google.com/site/scraphappymaryb/
Have fun!