I just finished a wingboard about 6 weeks ago. I learned on a 6'6" 115l board and decided I wanted to make something smaller but because I always seem to be out in conditions that are patchy where I need to get in potentially in displacement I mode I decided I was going to go for something in the 90-100l range. I think I nailed the brief pretty well. My next project will be one that is a little less user friendly in  terms of volume.. I went for 5'2" x26". 5" thick to get about 100l volume in the board so that once it was laminated the 6 or so kilos its would weigh would give me about 94l. I think I probably ended up at about 85-90l effective volume. Hard to be sure. It works fine for my 73kg. I learnt a few things that Ill share with you. I decided to use high density polystyrene at 2kg/m3 so that a 100l l blank would weigh 2 kg. I didnt want to skin the whole blank with PU foam -too much hassle for a homer. I also wanted to make it really bomber because I was using a harness and the hook can cause a bit of damage, also Im hard on my gear so I was prepared to sacrifice some weight for durability -cant have it both ways. I decide on a low rocker, essentially flat from midway to tail but using a deck that curved up a bit to keep some nose volume. Some have a flat deck so loose nose volume - a mistake IMHO. I also went for a flat bottom - no concaves blah blah blah. You watch. In 5 years everyone will have ditched the concave idea. At some point it creates derocker and increases your wetted surface area. I dont believe in concaves. I went with rail chines with a straight bevel, not contoured to the rail shape, to decrease drag and also wetted surface on take off. I put a tail kick but I really dont know if this is useful. Looks cool I guess. Usual high density patches for the fin boxes, handle, and a large deck patch for footbeds. Lamination was 2 layers carbon weave plus a uni strip in the middle and extra patches nose and tail and boxes. Handle on the bottom. No footstraps. It came out about 6.5 kg. Its really strong, like really strong. Super happy with it and it works in very light winds through to high winds. A real step up from the 6'6"in terms of performance.
So what would I do different next time?
I would go smaller, maybe aim for 80l to get a board of about 75l effective volume. I would use medium density polystyrene as with a good laminate it will still be strong enough. That should cut the blank weight by maybe half to 1 kg. I would do the same HD foam inserts but I would cover the entire deck with HD foam so that I could then laminate the deck with 1 layer carbon plus reinforcing for footbeds. save a bit more weight. I would laminate the bottom with 2 layers carbon, no uni patches. On the rails i would not overlap so much carbon. All in all I reckon I could save maybe 1-2 kg weight yet still be strong enough. smaller boards have less need of a harness, they are less heavy to fly.
I would put in footstrap plugs because smaller boards lend themselves more to jumping. I would also put 2 handles, one top and one bottom. The bottom one goes well back very close to the front of the boxes to balance with the foil bolted on.
Of course you need to use a vacuum bag. Almost impossible to do a good job without.
One other thing Im not sure about, maybe I'm imagining it. I notice some of the newer boards like mine look like they are riding in a slightly nose-down attitude. I think having the board taper very slightly to the tail, maybe only 2 degrees will mean that the board rides with the nose level with more even leg length. Ive never seen a fone board but the pictures of their boards look like thats what they do. Oh yeah be sure to put a goretex plug in when you have that much volume in your blank.
I have a theory that Im too chicken to try to build in case its a flop: It seems to me that wing boards never come up on foil by reaching planing speed. We wait for enough puff to pump the wing and pump the foil. So why do we use flat rocker? Surely this hinders pumping the board. Maybe we should have a curved rocker so the board pumps up more easily. Then no tail kick required because the rocker does the same thing, just better. I'll wait for someone else to test that theory.Have fun with your project. Its actually pretty easy.