Lockable Opinel Transport Case (No4 / No6 / No8)

Lockable Opinel Transport Case – octagonal Japanese wa-handle style

Why this case exists: The decisive driver behind the design is local law in Hamburg, Germany. Since late 2024, Hamburg bans weapons and knives of any kind on all public transport and in several additional zones (central station, Jungfernstieg, Landungsbrücken). Exempt from the ban is, among other things, transport in closed containers or packaging that prevents direct access. This case is designed exactly for that – deliberately conservative: the knife only becomes accessible after the padlock has been removed and the inner tray pulled out. Details on the Hamburg regulation (German): https://www.polizei.hamburg/waffen-und-messerverbot-oepnv-und-weitere-gebiete-999304

The octagonal outer sleeve is styled after a Japanese wa knife handle and houses a precisely fitted, removable inner tray. At the rear, a tongue on the sleeve reaches into a pocket in the tray's solid end cap. A standard mini padlock passing vertically through tongue and cap web blocks the only opening motion – the closed shackle encircles solid material and cannot be slipped off.

The knife doesn't sit in a negative mold but rests on three defined contact zones (Virobloc collar, handle belly, and the flared "fishtail" end) – tolerant of wood swelling and printing tolerances. Included are precisely fitted cases for No4, No6 and No8.

Features

• Positive mechanical locking with a mini padlock or combination lock (20 mm class: shackle up to 3.5 mm)

• Sleeve and test pieces print support-free; the tray stands on its end cap (no brim needed) and gets by with a few manually placed supports

• The grippy end cap covers the sleeve rim and serves as the pull handle for the tray

• Two sleeve variants: plain, or with flush-recessed leather inlay pockets (1.8 mm deep, suited to leather of approx. 1.5–1.8 mm) on the side facets – 1:1 cutting templates included as SVG, print them at 100 % scale

• Fit-test pieces (22 mm sections) to check the sliding fit before committing to the full print

Printing

PLA or PETG (PLA prints easily and stiff, PETG is tougher and more heat-resistant, e.g. for a car in summer; ASA possible). 0.2 mm layers, 4 perimeters, 5+ top layers, 25–35 % infill. 4–5 mm brim for the sleeve, the tray stands without one. All STLs are pre-oriented – just place them on the bed: sleeve opening up, tray end cap down. The sleeve prints support-free; for the tray, a few manually painted supports around the lock pocket and slot in the end cap are worthwhile.

Print test_shell + test_tray first, using the same profile as the final parts: the tray should slide cleanly by hand without binding or obvious rattle. If it binds, apply about −0.05 to −0.1 mm XY size compensation to the tray in your slicer (or +0.05 mm if it rattles badly).

Legal note: This case is designed as a lockable transport container. Whether and how such a container satisfies the legal requirements that apply to you (rules differ between German states and between countries, and they change) is for you to verify – this is not legal advice.