Joist reductions were historicaly cut with an axe. curved braces can be shaped with a chain saw or hewn with an axe. It is best if you can find naturally curved material for braces so that the grain follows the curve. I like live edge braces the best, look behind me in the picture I posted. All the braces over the book shelves are live edge, sawn on only two sides and the bark drawknifed off to follow the natural curve. Tom