I will not attempt to build my own because these are critical bits of equipment, that are very hard to build accurately. I will buy these from a Moth builder.
In the end I have a Fastracraft main foil from 2007 and a Aardvark rudder with a self made rudder stock. If you are thinking of getting foils shop around for your best option.
I experiments with flexible wands on my old boat and it was a waste of time. The control you get from a stiff wand is best.