Many years ago when I actually still had a baby I saw a bootie with a curved back like this.
I worked on the back for this years ago and put it away.
Mark the bootie backs for the casing.
Sew the bootie backs together right sides together leaving a gap for the ribbon to go through the casing.
Trim the seams back if you like so that the pieces will lay nicely.
I marked the 1" casing with a pencil.
My great grandmother used to keep a thin sliver of soap in her sewing drawer for jobs like this.
I remember seeing these thin pieces and not understanding why they were in her sewing drawer.
Sew the casing.
Remember to back stitch when you start and stop.
Iron your pieces.
Sew your bootie fronts together and press with an iron.
Pin your pieces together.
Make sure you pay attention and layer your bootie front over
the back to save taking it apart once it's sewn the wrong way.
I like to trim the middle layer back to reduce bulk before I finish the seams.
Zip around it with a zig zag.
Thread 25" of 1" ribbon through each casing.
I folded the ribbon in half to slide it through and then flattened it out where it exits the casing.
I secured the ribbon in back to stop a curious baby from pulling the ribbon out of the bootie.
I melted the ends of the ribbons over a candle.
I browned them a little bit.
Take a look at my other booties on my blog if you like.