Envelope-Lock Carton — A Glue-Free Top That Folds and Locks Itself Shut

The envelope-lock carton closes the way the back of a paper envelope does: four top flaps fold in over each other with angled edges that tuck and interlock, so the lid locks flat and stays shut by geometry alone — no glue, no tape, no pre-applied adhesive anywhere on the blank. That glue-free construction is the whole point. It means the carton ships as a plain die-cut blank you fold and lock by hand, so there's no folder-gluer step and no minimum order to justify a glue run — ideal for small batches, artisan and craft brands, samples, and anyone prototyping or hand-finishing. It also means the finished box is cleanly recyclable and repulpable, with no adhesive to contaminate the fibre, which is exactly the plastic-free, glue-free story eco-minded brands want to tell on pack. The interlocking fold itself reads as a deliberate design feature on the top face — a neat woven look rather than a plain seam. The base here is left open (no flaps), so the carton works as a hand-assembled cover or a bottom-fill box that sits over a tray or base. It's the glue-free counterpart to the pre-glued bottom-load display carton — same open-base idea, but hand-locked instead of machine-formed; and if you'd rather the base self-lock glue-free instead of the top, the self-locking box does exactly that. One thing to set right when you generate it: an envelope lock only holds if the flap angles and tuck depth are cut precisely for your board — enter your caliper accurately, because too little tuck and the top springs open, too much and the flaps buckle as they interlock. Then set your length, width, and height, and PackMyMan cuts the envelope-fold geometry correctly for your board, exporting a production-ready dieline in SVG, DXF, or PDF.