ShellyQ

Start a thread in the corner of a trapezoid as shown. Lay this along the edge of a square right sides together as shown (Pic12a)

Whip stitch this seam, starting at the star point and working outwards along the square (Pic 12b) Fasten off. I have chosen to stitch in this direction as we have to do a little finishing off on the outside edges and this is easier to do if you don’t have to start a new thread for just a couple of stitches

Restart thread back in the same corner of the trapezoid that you just started the previous thread. Turn work and fold, so that the pieces needing to be stitched, line up. Square will be facing you. Whipstitch this seam and fasten off

Add the next trapezoid in a similar manner (Pic 12c) working so that the last seam that you stitch will bring your thread to the center of the outside edge of the bock, (Pic 12d) where the overlapping trapezoids need to be joined