In these pictures it is easy to understand how the side walls of a hinoki tub are laminated.
First the material is assorted so that knots or other imperfections get discarded and of course, so that the total width of the planks is equal on the four sides of the tub. This is also a way to optimize the use of the material and avoid loss.
The wood is hand sawn by overlapping 2 planks so that with one single cut two perfecly matching planks are cut.
The pictures show the phase when the planks are drilled and connected with woodes plugs (dabo). The planks are joined with a waterproof bond and kept in the press overnight.
The corner of the tubs are realized with a more complex joint which is sealed by the insertion of hinoki wood bark which acts as a kind of natural gasket. Moreover, this bark has excellent fungicidal property and prevents mold stains in the most vulnerable point (the corners).