It was a pain, especially because of the little pieces! Very tedious and time consuming! I have my way of doing Wa handles from larger blocks, so using premade/preshaped pieces from other handles is a pain! The burnt chestnut handles are easy to do since they are often oval or D shape, so it's easier to shape. The octagon handles are more difficult trying to match the bevels and tapers, so I rough it on the belt sander, then clean up with sandpaper and granite reference plate by hand.
I used to do a lot of belt thinning, re profiling and re handling Japanese kitchen knives years ago, so I have all of the equipment still, but prefer to start with my method start to finish! The spoons were interesting trying to take weight off and not weaken them and the customer wanted a dark etch, not a polished stainless looking etch, so that took a while in my etching solution!