I measured the block size and it is 3 1/2 inches. I also measured down the side to the stitching line to get the measurement for my markings. The next step was to cut the base 3 1/2 squares and then the side pieces to a size that would cover the sides of the block after they are stitched in place. A method similar to paper piecing, only without the paper. It is also similar to the stitch and flip method that we all know using small squares to make triangles on large squares, where you stitch down the center of the smaller square and flip it up to make a triangle. I measured the rectangle to use as the flip side piece to be 4 1/2 x 2 inches. Here are my pieces--Next I put a mark 1/4 inch in on one corner and 1 1/2 inches from the opposite corner.
I drew a line from the side markings through the corner mark.
Place the base square and a side piece right sides together with the side peice extending 1/4 inch past the stitching line.
Stitch on the line--
Flip the side piece out and press--
Repeat for the other side piecce--
Flip again and press-- This is what it will look like at this point.
Turn the piece over and trim to the 3 1/2 base square.
Please comment and tell me how you would have approached this task.