- Place a piece 1 rectangle right side up on the reverse (unprinted) side of an A foundation. Secure with a pin or glue stick. Hold the foundation up to the light, printed side facing you. The edges of the rectangle must overlap all lines for piece 1 -- enough to create stable seam allowances when you sew on those lines.
- Lay a piece 2 triangle right side down on the rectangle, aligning its diagonal edge to overlap the printed sewing line separating pieces 1 and 2. If you're in doubt about which triangle variation to use, lay it right side up over piece 2 on the reverse side of the foundation to make sure its shape matches the space.
- Holding fabrics in place, turn the foundation over and sew on the line that separates piece 1 from piece 2, starting and stopping a few stitches on either side of the line. Remove from machine and flip piece 2 right side up. Check to make sure its unsewn edges overlap all surrounding seam lines for piece 2. If they do, trim the seam allowance to reduce bulk. Press.
- Place piece 3 right side down on piece 1. Sew to foundation. Verify placement and trim seam allowance. Press.
- Center a piece 4 triangle right side down across the tops of pieces 2 and 3. The triangle's long edge should overlap the point of piece 1 by 1/4". Sew piece 4. Verify placement and trim all layers of seam allowance. Flip upright. Press.
- Sew pieces 5 and 6 to the foundation in the same manner.
- Center an edge of piece 7 right side down on the foundation, using the tip of piece 1 as a reference for correct placement. Sew, check, trim seams. Flip upright. Press.
- Sew piecs 8 and 9 to the foundation in the same way.
- Sew piece 10 to the foundation. Use the tip of piece 7 as a guide to placement.
- Press. Trim all layers on the outer edge of the outermost foundation line.
- Make a total of four A units.
