6 Oct 2026 · TutorialsHow to Embed Hidden Magnets in 3D Prints

Hidden magnets turn a plain print into something that feels manufactured: lids that snap shut, fridge magnets with no visible hardware, parts that click together. The trick is to pause the print, drop the magnets in, and let the printer seal them in with a couple of layers. Here’s the method I use, with the tolerances that actually worked.

What you need

• Small disc magnets (I use 6 mm diameter x 2 mm thick)
• A permanent marker (a normal marker rubs off the magnet)
• CAD software such as Fusion 360, and a slicer that can pause at a layer
• Super glue (optional, but it makes the whole process easier)

Step 1: Mark the polarity

Put a dot on one face of every magnet before you start. When two parts need to attract, the magnets in one part go dot-up and the other part dot-down. Sorting this out mid-print, with the nozzle parked and the part cooling, is how mistakes happen.

Step 2: Print a quick tolerance test

Every printer and filament is slightly different, so print a small test piece with three holes: 6.1, 6.2 and 6.3 mm for a 6 mm magnet. Work in 0.1 mm steps. My results on a Bambu Lab printer:

Hole	Result
6.1 mm	Too tight, the magnet wouldn’t go in
6.2 mm	Firm press fit, stayed put while printing over it
6.3 mm	Dropped in loose, then got pulled out by the nozzle

That last one surprised me: the magnets are attracted to the hot end, so a loose magnet gets lifted out and dragged across the print. A loose fit only works if you glue the magnet in (Step 5).

Step 3: Design the hidden pocket

The magnet sits in a pocket just below the surface, so it’s fully enclosed once printing resumes.

• Depth: cut the pocket a little deeper than the magnet, 2.4 to 2.5 mm for a 2 mm magnet. A magnet that sits proud gets hit by the nozzle.
• Cover thickness: leave at least two layers above the pocket. At a 0.2 mm layer height that’s 0.4 mm. Don’t go to 1 or 2 mm: two parts with 2 mm covers put 4 mm of plastic between the magnets, and the attraction drops off fast.
• In Fusion 360: sketch the hole on the top face, then make the cut start from an offset of -0.4 mm (below the surface) and cut 2.5 mm deep. That leaves a hidden void with a two-layer roof.

Step 4: Add a pause in the slicer

In Bambu Studio:

1. Slice the plate, then use the up and down arrow keys on the layer slider to find the first layer that prints over the top of the pocket.
2. Step back one layer, right-click the + on the slider and choose Add pause. The printer will park the head at the back so you have room to work.
3. If parts need magnets at different heights (like a box and its lid), slice again and add a second pause for the next pocket.
4. Arrange parts near the front of the plate so they’re easy to reach, and add a brim to small parts so pressing magnets in doesn’t knock them loose.

OrcaSlicer and PrusaSlicer work the same way from the layer slider. In Cura, use the Pause at height post-processing script.

Step 5: Insert the magnets and resume

When the print pauses, check the polarity and push the magnets in, then hit resume. The nozzle reheats and prints the cover layers straight over the top.

The better way: glue. Press fits work, but they have a catch. On my second pause the part had cooled and shrunk slightly, and I needed a small hammer to get the magnets in, which risks knocking the bed. Now I make the holes 6.3 mm, put a tiny drop of super glue in each, and drop the magnets in. They set in about five seconds, the nozzle can’t pull them out, and there’s no force on the bed. Use only a small drop so it doesn’t overflow.

Tip: get the polarity right on every copy

Making several of the same part? Use a finished part as a jig. Let the magnets snap onto the finished part’s magnets, then press that part down onto the new one so each magnet lands in its pocket the right way round. Every lid then fits every box, and polarity is consistent across the batch.

Troubleshooting

• Magnet jumps out when printing resumes: the hole is too loose. Go down 0.1 mm or glue it.
• Magnet won’t go in on a later pause: the part has cooled and the hole has tightened. Glue with a slightly larger hole avoids this.
• Nozzle scrapes the magnet: the pocket isn’t deep enough. Add 0.4 to 0.5 mm to the magnet’s thickness.
• Weak hold: the cover is too thick, or the magnets are too small for the part. Keep the cover to about two layers.

Free model

The magnetic box from the video is free to download on MakerWorld. It’s a great first project for trying the technique.