The birdsmouth method of spar construction is quite brilliant in the way it enables thin timbers to create a light spar, and it can also save valuable material, but all that machining will also create waste. What interests me even more is that it might be an unnecessary complication that could prevent some people from attempting to make their own spars, especially if they don't own, or are intimidated by a table saw- and plenty of people are, for very good reason.
I'm really interested in processes that enable people, rather than intimidate them, and I wonder if, in part, our current fascination with the birdsmouth method is part of our tendency to look for technical improvements, even when they aren't necessary.
So, I'm building these spars as per plan- hollow the old-fashioned way, and rounded with a plane. I'll have more fun, less machine work and fewer exposed epoxy joints on the spars to soak up the UV radiation, and there maybe just the odd would-be builder that can see themselves achieving a nice mast this way. Using a plane is after all, one of the best things you can do for your mental health. Very few things come close.