There was more springback in the laminated wood than I was expecting. I will have to modify the form, or even make another form to end up with the right fender shape for the tire size. The wood ended up springing back around 8%, so I will try making a mould that is 8-10% over bent next time.
The three layers of 1.5mm ash are stiff enough when laminated. This gives a 4.5mm thick fender that is nice and light. Once it is braced to the bike through the brake mounts and by wire to the axle it will be stiff enough to ride with.
Because the fender radius is now too large it does not sit as close to the bike wheel as intended. The fender will also be trimmed thinner to look more proportional to the bike tire.