So now for part 3 of half-square triangle units.
The method described in Part 2 can be extended to make multiple pairs of HST units from just 2 pieces of fabric. For example, let's say that we want to make 6 HST units that measure 3" finished or 3 pairs. That means we need 3 times the fabric as for 1 pair of HST. So figure the fabric for 1 pair. For 3" finished we would need squares that measure 4" = 3" finished + 1".
For 3 pairs, we would need 3 squares that measure 4" x 4". If we cut them as 1 piece of fabric, we will need rectangles of each fabric that measure 12" x 4" or (3 times 4") x 4". To sew the HST units, we need to draw some lines on the back of one of the rectangles. First, mark lines to split the fabric into three 4" x 4" squares. Now draw diagonals across each square. The trick to make the sewing easiest is to draw the lines so that you can simply turn the fabric to continue sewing along the diagonals rather than having to cut the thread.
Lay the rectangles so that the 12" side goes from side to side. The lines that split it into 4" x 4" squares will be vertical. Now draw the diagonals starting at the top left corner to the bottom right corner of the square on the left and the one on the right. In the middle square, draw the diagonal from bottom left to top right. The diagonals will form a zig-zag path across the rectangle. Start sewing at a corner, turn at each edge to follow the zig-zag. At the end of the zig-zag, turn and follow the zig-zag back along the path along the other side of the lines.
To separate your 6 HST units, carefully cut along ALL of the drawn lines. Then simply press and trim as has been described in Parts 1 and 2.
This method allows you to handle larger pieces of fabric and saves sewing time. The time to press and trim is essentially the same.
Now this isn't the end of methods for sewing HSTs. More will follow soon.