Two-Piece Boxes Thanks to Laser-Cut Flex Hinges

It sounds like a challenge from a [Martin Gardner] math puzzle from the Scientific American of days gone by: is it possible to build a three-dimensional wooden box with only two surfaces? It turns out it is, if you bend the rules and bend the wood to make living hinge boxes with a laser cutter.

[Martin Raynsford] clearly wasn’t setting out to probe the limits of topology with these boxes, but they’re a pretty neat trick nonetheless. The key to these boxes is the narrow to non-existent kerf left by a laser cutter that makes interference fits with wood a reality. [Martin]’s design leverages the slot and tab connection we’re used to seeing in laser-cut boxes, but adds a living flex-hinge to curve each piece of plywood into a U-shape. The two pieces are then nested together like those old aluminum hobby enclosures from Radio Shack. His GitHub has OpenSCAD scripts to parametrically create two different styles of two-piece boxes so you can scale it up or (somewhat) down according to your needs. There’s also a more traditional three-piece box, and any of them might be a great choice for a control panel or small Arduino enclosure. And as a bonus, the flex-hinge provides ventilation.

Need slots and tabs for boxes but you’re more familiar with FreeCAD? These parametric scripts will get you started, and we’ll bet you can port the flex-hinge bit easily, too.

Box Maker extension for Inkscape

If you use Inkscape to lay out your laser cutter designs you might want to look into this box maker extension. Inscape is [Elliot’s] drawing software of choice since it’s easy to use, and it’s open source. After having to lay out the tabs for a box he decided it was worth his effort to develop a tool to do this automatically. The extension works inside of Inkscape, letting you start your projects with a set of automatically generated box sides.

The input window for the extension leaves you plenty of options for the joint design. In addition to the size of the box (inside or outside measurements can be selected), you need to enter the thickness of the material, the kerf size (how wide the cut will be), and how much clearance you want between the teeth. The width of the teeth is also configurable.

Our feature of a laser cut replacement case is what prompted [Elliot] to tip us off about his extension. That project used a web-based parts generator to do the joint design.