I just bought a dozuki which seems a beautiful little saw. I decided to make a sheath for it to protect the blade, and based it on one I have fitted to a gent's saw I scored, obviously made by the previous owner.
Pretty basic but sufficient, it has two sides of 3mm ply glued to a spacer of leather, thick enough to suit the blade. I then drilled and fitted 3 copper roves for reinforcement, and fitted a leather band to secure it, which simply slides away to remove the saw. The trick is a triangular cut-away on one side of the ply to help slide in & out the saw. The leather band is secured by an ingenious little join which I think you can work out, simple but effective and the original fitted to the gent's saw has held up to constant use for 25yrs.
A folly perhaps but satisfying Now to really use the saw
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