I've made 1! After I had cut/mounted all of the shirts I laid them out on the floor. Sat there and thought....holy crud what have I gotten myself into. Then I took a breath and arranged them the way I wanted.
Once arranged I:
sewed sashing onto each block within a row to make them all the same height. This meant some had wider sashing than others because some Tshirt fronts were small. After I sewed each row whatever height the tallest shirt was in that row I laid them out again.
Then, I took and looked at the columns. I had to then make the squares within the columns the same width. So, I looked at the widest one in a column and were that wide.
Now I had sashing on all 4 sides of each shirt, but they worked going across in rows and up/down in the columns.
Then I sewed a narrow strip of black between columns/rows. This helped the sashing not all run together. I also put a black narrow border around the outside of all the blocks.
I love it! I'm so proud that I was able to figure out this overwhelming task. I can't post a photo now. I'll come back later and do that so you can see what I did.
I'm sure there are easier ways, but I wasn't able to find anything as my shirts too were all different sizes to start with.