Our lattice strips were made of a cherry printed material. The number of lattice strips will depend on how many quilt block you end up making. Our quilt was 3 squares wide and 4 squares long... and it turned out a little small. (It would be perfect for a child's bed.)
Cut strips to 3" x 12.5". You will need enough to connect the squares together lengthwise (Block A to Block B), plus a strip on the outside edge of each row. In our case, we cut 16 of these pieces. Sew all of the Rows together... (using 1/4" seams)
Then you need to cut lattice strips that will go the entire length of the rows. We have 4 rows, so we cut 5 of these lattice strips... 3" x the width of you quilt... ours was 46" long.
You may want to frame your quilt with wider lattice pieces on the outside eges, or even do a second border around the quilt blocks to add a little more depth. to the quilt.