When your block is complete pin all edges that are flapping in place by placing the pins inside the sections on the perimerter of the block making sure all fabric is smooth and/or flat.
Turn the block over and using a ruler that has a 1/4 inch mark, place the 1/4 inch line on the sewing line of the block... on this project it is a dash line about 3/8 inch in from the solid line of the outside edge of the printed block.
Holding the ruler in place... trim with roatary cutter to give the block the 1/4 inch seam allowance. You may also simply trim using the 3/8 inch that was drawn on the block template. Whatever way you use... remember that when you go to sew the blocks together. I trimmed to 1/4 inch as I generally use a 1/4 inch seam allowance for my piecing. Continue this procedure on all 4 edges of the diamond.
The block will look like this. I am not sure I like my color combination in this picture. I may have to to another block.!!!!!