Double-sided ribbed roman shade- at last!

I've been wanting to try making one of these for years.  A double-sided shade lifts from cords sandwiched in between two shades which fold up independently of each other.

At last the perfect opportunity arose: for Denise Wenacur's client, a basement space with a playroom and a gym, with a window between so the adults can see the children.  They wanted two shades, one in each room, but I thought I had an even better idea.
It worked perfectly.
From the gym you can operate the shade and see into the playroom.

 On the playroom side, you can see through the window the valance that hides the clutch and the grommets that allow the strings to lead up to the headrail.  The pleats fold up neatly thanks to the ribs inside.

Before making the client's shade, I needed to make more than a mockup- rather, a full size sample.  As I made it I thought of better ways to do it, so the final product isn't made quite like this one was.

Both shades have this in common: the ribs are secured in the side hems.  For the mockup, the ribs were tucked into the side hem which was secured with Sealah tape.  For the customer's shade, the side hems were hand-sewn.

 

 Twin stitches were made through both layers and provided a channel for the lift cord.

The actual shade was lined, with a sheer, to keep bulk to a minimum.  The lift cord was secured at the bottom, inside where the weight bar will be sewn.   An X-shaped stitch on the front side only created the channel for the lift cord, and when it was all assembled and hung, stab-stitches were made to hold the layers together.

On the playroom side the valance hides all the workings, and at the ends small flaps keep the underside of the board out of view.