Slowly and carefully, I'm adding the background to the 3D project on my design wall. Here's what it looks like today.
I'm adding the background strips to the top and bottom of the pieced strips, then stitching two adjacent strips together into a pair. This requires measuring for the background lengths, lots of pinning to match the seams, and carefully pressing the seams open to control the bulk of the seam intersections. Slow going!
After all the pairs are made, I'll again join two of them together into columns, to work with manageable sections. Then the halves of the top, and finally the two halves together. This project is huge, about 98 inches square, and as it gets assembled it'll require some serious wrangling.