I have done simple “I Spy” quilts. I have used 5” squares of themed fabric. This is easy to swap with othe quilters. Then you can pick a bright color to put in as sashing. I have done 1.5” unfinished. Then use this or a bit wider 2” to border. Then I use a tonal print outer border to bring it all together at about 5” width. The grid of squares is usually 5 x 7 so it creates a nice size.