Well its going on 2 years since I started the first foil build, since then I have learned alot about foils, what makes them work well and what doesnt as well as refining my build methods , ( still wood core and carbon). Its also been valuable to have ridden many different foils of various brands and sorting out which characteristics of each I like or dislike and what exactly provides those characteristics to a given foil, the small details in a given design make huge differences in performance. since I am now at the stage of being comfortable carving waves on a foil ( wave/surf kiting has always been my passion) I am trying to achieve the best foil for freeride/waveriding possible, what I have found is a light foil and board is more reactive and easier to make minor adjustments quickly, a short board with less swingweight is a pleasure to ride, my favorite at the moment is 120cm ( 4 ft x 19in) and light @ 6lbs. a shorter mast ( 35 in) feels more "carvable" on waves and more solid under foot with no decernable drawbacks ( since I dont race).
As for the foil specifics I started out building foils with low speed glider type airfoils, rather blunt entry with the high point of the foil at about 25%, same thing with the mast , I have since moved the high point back to around 40% with a fine leading and trailing edge, the first foils were forgiving to ride, slow and made noise the later foils are much faster, still very stable, super reactive to rider input and quiet as well as having very low speed foiling ability.
The plan form ( outline) design of the wings has also progressed , I have tried flat wings with winglets like the " Stringyfoil" Greg of BRM rides which worked very well although different than anhedral/ dihedral wings which I prefer, I also prefer a mid aspect wing for the type of riding I do.
So far many people have learned to ride on my foils, all of which have taken alot of abuse and are still going strong, all but one have been reshaped with a big performance improvement.
Anyway, its been a long road of building , discovery and learning to ride well enough to know what I want, I am just now finishing foil # 7 and believe it is another big step in the right direction, foil with board is just under 12 lbs. hopefully within a month or so I'll be able to give it a test along with my new LP FRS foil.