Piecing a square-in-a-diamond

Here's an easy way to align square-in-a-diamond units:
1. Layout the pieces. You'll be sewing together the pieces that are opposite from each other.




2. Stack up the first two triangles that were opposite from each other with the point pointing down. Trim off exactly 3/8" from the tip. Flip the two triangles over and trim off 3/8" from the other side, too:
3. You'll have two pieces that look like this:
4. Sew the two pieces to the square and press open:

5. Repeat with the other side: stacking the two triangles, trimming off 3/8" of the points from both sides and sewing on the two triangles. Press open: