I've made several of these. Several were cut all same size and several were cut using various sizes. It's fun to do different sizes, but you have to watch as it can get to be a geometric nightmare. The best one was having the t-shirts cut based on three inch grids, meaning 3", 6", 9", 12" squares. Then I used 3" charm blocks for the sashing throughout. Turned out great! My daughter loves to use it at college. The back of it is more t-shirts with teal sashing based on a two inch grid. Had it machine stitched and it is used constantly! Have fun with yours!