This model contains strong magnets. It is not a child's toy.
Behold the forgotten technology of ancient Egypt! The Enigma Tower defies natural law by suspending an object along its axis of unstable equilibrium. What was once deemed impossible was solved long ago, only to vanish, lost to the unrelenting sands of time.
For this project, it's important to carefully follow all directions, especially the safety instructions (feel free to skip over the “Physics” section). Otherwise, rather than deal with poor results, I suggest moving on to a different project.
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Physics
This project resolves a 25-year-old disagreement with my physics professor.
Earnshaw’s Theorem states that you can’t achieve a stable static equilibrium of charged particles using only electrostatic forces. One outcome of this is the inability to stably levitate an object using stationary electric fields. Any slight displacement pushes the object away rather than restoring it to equilibrium.
That’s why levitation devices (like this one which I highly recommend) generally incorporate active stabilization electronics. By continuously adjusting electric fields based on measured displacements, they maintain levitation. However, active systems require constant power, can overheat, and need careful setup each time they’re run. In contrast, passive stabilization avoids those pitfalls, which is why it fascinates me.
To illustrate Earnshaw’s Theorem, my professor used the classic example of trying to levitate one disc magnet over another by facing their poles opposite each other. Anyone who’s tried this knows it’s impossible to achieve stability. He correctly stated that no combination of magnets/orientations would let you levitate one disc magnet over another. Then he overgeneralized, saying magnets couldn’t stabilize an inverted pendulum unless it was physically connected.
My claim was that a single point of friction might be enough to evade Earnshaw’s Theorem, and that with the right magnet configuration, you could stabilize a disconnected inverted pendulum. I even had a design in mind, but couldn’t make it work back then.
Over the years, I found examples that, in my view, supported my claim. Yet my professor always found reasons they didn’t count. What I needed was a “pure proof.” With modern precision 3D printing (my P1S printer), I finally managed to iterate and fully realize my design, something not feasible with traditional tools.
Even better, The Enigma Tower achieves passive stabilization without surrounding the object with magnets. The only magnets are inside the stabilized object and directly underneath it (the flaps on the side are purely decorative and do not contain magnets). Furthermore, while I could have proven my point with a long, skinny inverted pendulum (a more inherently stable shape), I chose a classically unstable shape (a pyramid inverted on its tip) for extra flair.
In fairness to my professor, he wasn’t the only one who said I was wrong. I was told this was impossible (unless the object was spinning) by folks on Reddit (r/physics) as well as by the latest ChatGPT model. The only encouragement came from Physics Stack Exchange, but that approach required much stronger magnets. I wanted a more elegant, compact solution.
Update (1/4/25): I finally heard back!
Hey Mike,
I took a look at your design, and I have to admit I’m surprised that the fields didn't fully negate. It seems you’ve found a sweet spot that keeps the pyramid balanced in a way I did not expect. While I still maintain that Earnshaw’s Theorem generally applies under standard conditions, I can see that this particular setup doesn’t strictly fall under the typical scenarios we discuss. It’s always insightful to see how real-world configurations can behave.
Good job seeing this project through—clearly you’ve put in some hard work. Let’s stay in touch if you decide to push it further.
Best, <Redacted for privacy>
Required Materials
Most generic magnets are unlikely to have the precise strength required to achieve proper balance - I've tried and had comically bad outcomes! Please use the Bill of Materials magnet links for best results and to support me - thank you!
Nine (9) 4×2 mm round neodymium magnets from Maker’s Supply (see Bill of Materials – 1 pack is sufficient). If you don’t already have a magnet insertion tool, you’ll need two additional 4x2 mm magnets (total of 11) to create one, but either way 1 Maker’s Supply pack is sufficient unless you want to print more than 2 pyramids.
Five (5) 25×3 mm round neodymium magnets from Maker’s Supply (see Bill of Materials – 1 pack is sufficient).
Super glue – The tight ring of magnets in the pyramid can eject its magnets while you’re inserting them. A drop of super glue prevents this, even if dried only briefly.
(Optional) Stainless steel nozzle – this type of nozzle doesn't attract magnets, whereas a hardened steel nozzle can yank magnets out if the glue doesn’t hold. But if you monitor the print for the next few layers after inserting the magnets, and are ready to take prompt action if needed, hardened steel should be fine (it’s what I used).
(Optional) Holographic-effect or smooth build plate – A textured plate works but may not look as nice for the pyramid base or obelisk flaps.
(Optional) Acetone – You’ll probably get super glue on your fingers. Acetone can help remove it.
Check that all magnets are in good condition, free of chips, to ensure maximum potency.
Consistency of Magnet Strength
Magnet strength (and size) varies drastically by manufacturer, so using neodymium magnets from Maker’s Supply is critical. My earlier prototypes were dialed in using cheap generics, but when I switched to Maker’s Supply magnets, my pyramids rocketed off the base. I had to recalibrate everything. My precision calibration is now based on Maker’s Supply magnets received in November 2024 (also replicated with magnets received in January 2025). If they switch suppliers later, results could change. In any case, these are inexpensive parts. Just add them to your next filament order to save on shipping!
If your pyramid sits slightly askew, my best guess is it's due to minute differences in magnet strength. While the askew pyramids have their own charm (standing without even appearing balanced), I've published an “alternative pyramids” profile for folks seeking perfect balance.
If you decide to use other magnet suppliers and are ok tinkering with calibration yourself, note that size also varies significantly among brands. For example, the Maker’s Supply “4×2” magnets are just under 2 mm thick, but the cheap generics I had were about 1.65 mm thick. I expect some magnets could exceed the thickness of the Maker’s Supply ones, and if they protrude above your printed surface, they could damage your nozzle.
Safety First
Neodymium magnets are not toys.
Keep them away from pets and young children. Swallowing two magnets can clamp them together inside the digestive tract, leading to severe injury or death if not surgically removed.
The 25×3 mm magnets are relatively strong. Keep away from pacemakers, and avoid handling them near other magnets or ferrous metals. If they freely collide, they can break or cause finger injuries, and shards can fly off and injure your eyes. They typically ship with spacers which will need to be carefully removed. A good technique is to stack them one at a time, carefully sliding the next magnet onto the stack from the side and then releasing once it begins to slide into place.
How to Print
The filament colors I used are listed in the Bill of Materials, though I also used a generic black silk (Bambu does not currently sell such a color).
Obelisk
Just print it. You’ll insert its magnets afterward (see “How to Assemble”), and they’re not secured in place so that you can adjust them if needed.
While it’s tempting to print the obelisk upside down to reduce the height of the prime tower, even with supports the quality of the hieroglyphs drops significantly in that orientation. That said, having a prime tower at all might not make a big difference for this model, so disable it if you wish, but I haven’t tested that. I’d leave it enabled for the flaps, though.
Pyramid
If using my settings, you can ignore Bambu Studio’s “floating regions” warning.
Update (1/5/25): I've added a new print profile with additional pyramid sizes. Most users should just stick with the regular profile, but if you're having issues with balance, a smaller pyramid may help. The instructions below are still applicable except that the pauses are at different layers for these smaller pyramids. Regardless, I've already configured the pauses for each pyramid, so you're good to go.
Update (1/11/25): Another theory for the inconsistent floppy pyramids is that clumps sometimes get deposited inside this hollow model, causing a weight imbalance. Imperfections can appear near the pause layers because there’s no prime tower at that height. A possible solution is to add a narrow cube as a makeshift prime tower, matching the model’s height. This also helps sharpen the pyramid’s tip, giving the rapid top layers extra time to cool. This technique helped another project I'm working on, but I haven’t yet back-tested it. If anyone else tries it first, let me know. If it helps, I'll update the print profiles accordingly.
First pause - layer 235:
Put a tiny drop of super glue in each of the six ring slots.
Insert one 4×2 mm magnet into each slot. To reduce the chance of them popping out, place magnets in alternating slots first. The N side of each magnet should face up, so use the S side of the insertion tool to position them.
Inserting the last few magnets can be tricky because neighboring magnets attract them. Pin the magnet between the tool and the ring rim, just above the slot, and slide it in. Cover neighboring magnets with your fingers if needed (yes, you’ll likely get glue on your hands!).
After inserting magnets, verify proper orientation (polarity) by confirming the N side of the insertion tool is repelled by each inserted magnet. Don’t use the S side of the tool since you might pull the magnets back out.
Ensure magnets don’t extend above the print surface (to avoid damaging your nozzle).
Wipe off any excess glue and resume printing.
Second pause - layer 279:
Insert a stack of three 4×2 mm magnets into the center hole. The stack’s S side should face up, so use the N side of the tool to insert it.
Update (1/5/25): If printing one of the alternative smaller pyramids, pay attention to the name I set on the plate in Bambu Studio. One of these pyramids requires a stack of four (rather than three) 4x2 mm magnets in the center hole - this is noted in the plate name.
Once again verify polarity, ensure the magnets don’t protrude and resume printing.
How to Assemble & Display
Insert the flaps into the obelisk. No glue required.
Stack five 25×3 mm magnets, removing manufacturer’s spacers carefully. Refer to “Safety First” above for important handling tips. If you truly wish to conserve magnets, you can use a couple fewer in your stack. To me, 5 feels near the point of diminishing returns. If you use fewer, you'll need to print extra spacer discs for the next step.
Pack the obelisk:
Insert the magnet stack with the N side facing up.
Insert all of the spacer discs, not to be confused with the manufacturer’s spacers (from the prior step) which can be thrown away.
Insert the stopper. If you ever need to remove it, just shake the obelisk. The weight of the magnets should pop it out. Catch them so they don’t come flying out!
If you previously downloaded this model, the original stopper was 15mm shorter since my prior instructions used a stack of ten 25x3 magnets. That guidance may have been overkill, though you can certainly stick with it. Alternatively, just print the new stopper so you can use fewer magnets.
Balance the pyramid by resting its tip in the small divot atop the obelisk.
If the pyramid is pulled down too strongly, you probably inserted the 25×3 mm magnet stack upside down. Flip it and try again.
If it’s pushed away and won’t stay in the divot, move some spacer discs above the magnet stack.
Thank You!
Enjoy your Enigma Tower! It’s fun, educational, and a testament to the power of patient tinkering and precise 3D printing!
The hieroglyph imagery is derived from public-domain sources, including historical artifacts, and generative fragments curated and arranged by hand. All model geometry, engineering, and balance effects are original and manually designed.
Finally, here's me playing around with an early prototype of a smaller pyramid. Since it doesn't require as much repulsion force, I was able to configure the magnets in a way which lets it stick in interesting ways. I've now provided a slightly larger and fully themed version of this in my “alternative pyramids” print profile. Please read the description of that profile for more details.
MembershipYou can always print this model for yourself or to gift, for free. Selling prints requires a tier 1 or higher membership. The allowed sales quantity is specified within each tier's terms.
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