I've had several PMs wanting the instructions for the center of my op art quilt. I used a black/white striped fabric to make my quilt. The stripes were an even 1" wide across the fabric. The center of the quilt finished out about 45" square.
I have no problem sewing partial seams, so I assembled the center by sewing sections A-E and G-H together. The stripes in those sections have to match up perfectly. The I sewed both A-E and G-H to section F. Those section stripes have to match up perfectly. The remaining sections can be assembled and sewn to the AEFGH section. The stripes have to match in CD and JK, but don't have to match with the previously assembled AEFGH section.
Then I added the four corner triangles. The corner triangles around the center of the quilt were made by cutting two 36" squares of black fabric in half diagonally. After the four corner triangles were attached, I squared up the quilt center to about 60" square and added the first narrow border. I use a 2" geometric border. Then I added a 5-1/2" black border and then a 7" geometric border, and then finally, a 2-12" black border. The quilt finished out about 95" square.