I was challenged to make a Nagauta bachi, so I did.
For this, I laminated two corian tiles together and rough cut the profile on the bandsaw.
I then shaped the sides with my custom sanding block I made for shaping the side profiles of bachis. With the side profiles established, I applied a bladed finish with a fresh razorblade.
The rest of the time was spent hand grinding the faces on an engineer’s block. Once each face was flat and even, I worked through the grits until reaching a finish I was satisfied with and a suitable edge.