Tapered box pleat valance

This is one of my favorite valance silhouettes: a barely rounded arch that reads more like a taper after pleating.  Combined with the added dimension of the double box pleat in the center and the knife-pleats at the ends, the simple shape acquires depth and movement.

The fabric had a mind of its own, so the night before the valance was stapled to the board, the pleats were pinned into place on the work table.

They were left weighted down until morning, and this self-lined valance pleated up perfectly on the board.
In the foreground you can see my diagram.  I have to draw out every detail to make sure I don't omit a pleat, or something, and to plan seams so it doesn't accidentally land in the front.