I did some research and texted a friend as to what kind of fusible interfacing to use, she suggested Pellon 44F at 99 cents a yard at Jo-Anns. It is 20 inches wide, so I bought 12 yards. My rationale was 2 shirts per yard, cutting the fusible 18 by 20 inches. Everything I read said to cut the shirts up the side and across the neckline...then apply the fusible before trimming the shirt to the correct size.
I then measured each front of the shirt with the design side up to see what a common size would be to cut. A friend loaned me plastic templates, a huge time saver....most of the shirts could be cut to 12.5 inches square, but 4 were too big and needed to be 14.5 inches square. So, I trimmed them all to 15 inches. I decided to seam two of the shirts together to make one shirt and did this twice.
There was one shirt left when they were all laid out 4 x5, but I decided not to use that one.
My plan is to add a frame around each shirt and a white strip in between, even without borders, I realized this quilt will be big...!!! My husband (the engineer) suggested making the first and last column narrower (12.5 x14.5) and the center row smaller. (10.2 x 14.5)
It seemed to work visually, so I started auditioning fabric strips to frame the blocks.
I didn't realize how labor intensive a "T-shirt" quilt is to make.
Finally! All of the frames are sewn and I added white sashing around all of the blocks. The 3.5 inch flowered border has been added and it's off to the longarmer.