Round box Pro

How it goes together

The wall is a single strip. It is cut straight and bent into a circle: what looks like a grid of slots is a living hinge, and it works because each slot removes material exactly where the MDF would otherwise have to stretch.

There are three patterns and they change how far it bends. With straight slots what flexes is a short stubby bridge: little leverage to spread the bend over, so it bends little and cracks. Wavy leaves an S-shaped ribbon between two columns — the same millimetre of wood, but with a longer run — that can twist as well, which is what really lets it curve. Eyelets no longer just cuts: it removes material, so it bends the most, holds the least and shows the most.

The wall carries the tabs, and the base and the collar carry the slots they go into. Each tab is exactly one band of the hinge: the hinge splits the strip into vertical bands as wide as the slot spacing, joined to each other only by the bridges, and a tab that starts and ends where its two neighbouring columns do has them running along its sides instead of through its root. That is why its width is not chosen separately: it comes from the spacing.

That way the hinge reaches all the way to the edge. The first version of this template deleted the column of slots that landed on each tab — it would have cut through its root — and that left eight rigid millimetres every twenty, nearly a fifth of the way round with no bend in it. Now no slot is missing and the tab hangs off a band that bends like all the others.

The base, the collar and the lid stand out past the wall. That rim is not decoration: the slot takes up the whole thickness of the wall, so if the disc ended exactly where the wall ends there would be no wood outside the slot and the slot would really be a notch open to the edge — it snaps as the tab goes in. With a lip the joint ends up enclosed and held on all four sides. Set it with “Lip”; below a millimetre and a half the warning complains.

The slots are straight, even though the piece is round. A tab is a solid eight-millimetre piece and it does NOT curve once the strip is bent — what bends is the hinge beside it — so a curved slot would make it bind on its own corners. Straight, it goes right in, and what strays from the arc over those eight millimetres is a tenth of a millimetre, covered by the tab itself.

The top is a collar, not a disc. It is what keeps the mouth round with the lid off — without it the wall springs open — and it is what the lid rests on. Its opening is the real mouth of the box.

The order of assembly matters. The strip closes around the base and the collar, not before: they are what give it its shape. Work the tabs into their slots — the base first, then the collar — true up the ring, and only then glue the seam with a band of tape around it while it sets.

If the lid is cut through, the piece under it is a ring. A solid disc behind a cut-out is wood where the inside of the box should show: the opening would meet another piece three millimetres behind it. That switches over on its own when you pick cut-out or negative text.

The seam falls on the flattest part. On an oval that is the long side; on a circle it makes no difference, because the whole outline is equally flat. It is butt-glued: the two ends of the strip meet edge to edge, with no overlap. What holds it is the tabs on its two bands, not the glue: one starts right at the joint and the other sits one band away on the other side, both fitted into the base and the collar. One and not two, because two tabs side by side would leave their slots separated by a tenth of a millimetre of wood, which snaps on its own.

The diameter has a minimum and it is worth respecting. The tighter the curve, the more each bridge is stretched; past a certain point the MDF cracks and snaps. The warning works out the minimum for your thickness. On an oval it is the end that decides, and it curves tighter than a circle of the same size: a 300 × 80 oval bends at its ends as if it were a 21 mm box.

The length of the strip is measured on the inner face, which is the one that sits against the step of the discs and the one that has to go round exactly — the outer face stretches. And on the oval the perimeter is integrated rather than estimated: an ellipse has no closed formula for it, and the well-known approximations are off by just enough to leave the seam open.