Years ago I made a lap sized one. I used Mary Ellen Hopkins book and templates. Did it all on the machine, and it all just fell into place - and it was my first attempt at machine 'piecing'. Even the 'corner stones' were easy. The secret to doing them was to attach the arcs to the melons. When you had all them stitched together and just had the holes for the 'corner stones' left to do, you make a four patch, stitch that to one side, then the opposite side, then do the other 2 sides the same (i.e. N&S, then E&W). Repeat for the remaining ones. Fiddly, but I didn't need to unpick one stitch in the whole top.
I'm now looking for the fabric to make one for my bed.