Free laser box maker with finger joints
Make a finger-jointed box for your laser cutter, free and in your browser: set the inside size, the material and the kerf, and get the panels as a real-size SVG laid out on your bed. Open top, closed, or with a lift-off lid.
Faster with the free Chrome extension: right-click any picture on a website and send it straight to the laser box maker. Add to Chrome · what it does
Extension installed. Right-click any picture on a website and choose Makerfern → Open this picture in… to bring it here.
Joints that fit the first time
A box generator is only as good as its fit. Every panel here is worked out at the outside size, fingers and slots cut from an odd number of equal steps so both ends of an edge match, and then every outline is pushed out by half your kerf. The beam burns that half away again, so a tab comes out exactly as wide as its slot. The panels are checked in the test suite by assembling them in 3-D and confirming every cube of the walls is filled by exactly one panel, with no gaps and no clashes.
What you get
- The panels at real size, laid out on your bed with a gap between them, in as many sheets as it takes.
- Inside and outside sizes, so you know what fits in it and where it will fit.
- Panel names in a separate colour, so assembly is not a puzzle.
- A warning when fingers are too narrow for the material, the kerf looks wrong, or a panel will not fit the bed.
Settings that matter
- Measure the material. A sheet sold as 3 mm is often 2.8 or 3.2. The fingers are cut to the thickness you enter.
- Measure the kerf with a 20 mm test square, then cut one corner joint in scrap before the whole box.
- Leave the finger width at 0 unless you want a look: it picks about 2.5 times the thickness.
Questions
What is kerf, and what number should I use?
The width of material the beam burns away. Without allowing for it, every finger comes out a little thin and every slot a little wide, and the box rattles. Cut a 20 mm square, measure it, and subtract that from 20: that is your kerf. Most diode and CO2 lasers land between 0.1 and 0.2 mm in 3 mm plywood. The tool adds half the kerf all round every panel, so fingers come out wider and slots narrower by exactly that much.
Inside or outside sizes?
Inside, by default: the space that has to hold something. The walls are added on. Untick the box to give the outside size instead, for a box that has to fit a shelf or a drawer.
How does the lid work?
The lid is a shallow open box turned upside down, sized to slip over the outside of the box with the clearance you set. It lifts straight off; no hinge, no glue on the lid.
Does it work with LightBurn, xTool and Glowforge?
Yes. The SVG is drawn at real size in millimetres with red hairline cut lines, which LightBurn, xTool Creative Space, Glowforge and Inkscape all open at the right size. Panel names are in blue so you can engrave them lightly or delete them. Pro adds DXF, one file per sheet.
Do I need glue?
A snug finger joint holds on its own for a test fit. For a box that will be handled, run a little wood glue along the fingers; for acrylic, use acrylic cement.