Sinusoidal notches for locked crossings

The best profile for the notches seems to be roughly sinusoidal, as seen in this template which I have been using with a 3/16" hole punch and strips of aluminum flashing that have been averaging 1.47" wide (I had aimed for 1.5"). The black discs are for visually centering the punch when the cardboard template is punched. Even at this relatively coarse scale of weaving the notching must be done at an accuracy that is pretty demanding for handwork (all of this could be avoided with a steel rule die to punch the whole 4-notch crossing in one blow.)

The image above shows via backlighting the four little lens-shaped openings or engagement windows that are the inevitable consequence of the material's non-zero thickness. A precise design needs to accomodate this geometry.

The fourth notch is engaged by bending the sides of both weavers upward, as in the photo below: