While roasting a leftover turkey carcass to make soup stock I was able to get some sewing done. The top of the side panels were sewn together, then the top and bottom seam allowances were pressed and graded. Here is the corset before I flipped it to sew the channels. The front is wrong side out, with the center front in the center, and the the back is face up.
The 1 1/2 inch wide ribbon has just enough width to fit four 5/16 inch wide channels. So after the side panels were basted together I sewed down the center of ribbon, measured and marked 5/16 inch with removable artist's tape, and sewed.
It's looking like a corset! This ribbon corset already looks neater than it's 1904 cousin. If I don't screw up the grommets it may stay that way.