How to design a laser-cut wood finger joint (fingerbox) connection in Autodesk Inventor

thijs · September 2, 2026, 12:15am

Based on contributions by Job_Valkenburg.

A finger joint (“fingerbox”) is a strong, glue-free way to join two edges of laser-cut wood plates. This shows how to add fingers to one shared edge between two already-designed parts in Autodesk Inventor; repeat the same process for every edge of your part that needs joining.

What you need

Autodesk Inventor. It’s free for students — see the Autodesk education access page to sign up.

The confirmation email is often delivered to your spam folder, not your inbox.
Basic familiarity with Inventor sketching and part modelling.
Two wood plate parts you want to join, fully defined (no dimensions left free to change).

Steps

This example joins two wood plates as shown:

Make sure both parts are fully defined before you start, so no measurement can shift while you’re joining them.

1. Sketch the fingers on Part 1

Enter the sketch of the first part and sketch a “finger” on the edge you want to join. Set the finger’s height equal to the thickness of the plate of Part 2 — that’s what the finger needs to slot into. The finger’s width is less critical; keep it in the 10–40 mm range.

2. Pattern the fingers on Part 1

Use the Rectangular Pattern tool to repeat the finger along the edge:

Select the three sides of the finger.
Click the arrow at “Direction 1”.
Click the line along which you want the fingers to repeat.
Set the spacing between fingers to double the finger width.
Fit as many fingers on the edge as possible, adjusting by trial and error.
Click OK.
Extrude all the finger surfaces.

Part 1 is now finished.

3. Sketch and pattern the fingers on Part 2 (inverted)

Do the same on Part 2, but inverted — Part 2 gets slots cut in, rather than fingers sticking out:

Sketch the finger shape into the part instead of on top of it.
Set the distance between the edge of the finger cutout and the edge of the part to the same length used on Part 1.
Use Rectangular Pattern the same way as Part 1.
Extrude everything except the fingers (i.e. cut the finger slots out, leaving the material between them).

The result looks like this:

4. Check the fit in an assembly

Constrain both parts together in an assembly to verify the fingers mesh correctly before sending anything to the laser cutter.

Troubleshooting

Fingers don’t line up between the two parts — recheck that the finger spacing (double the finger width) and the starting offset from the edge match on both parts.
Joint is too loose or too tight — the finger and slot dimensions in this guide are nominal (no laser kerf compensation). Check: if your fit is consistently loose or tight, ask the workshop about the laser cutter’s kerf width and compensate the finger/slot dimensions accordingly; this wasn’t covered in the source material.