The Haunted Lincoln Illusion

Engineering + Art = Magic
Beginner's Guide	The Next Dimension	How It's Made

A classic illusion, like those famous ones in theme park haunted houses, where a head seemingly turns to follow you. It's hard to capture how mind blowing it looks in person. Display using the simple instructions at the bottom.

The Haunted Busts

Due to the fantastic reception of this illusion, I'm releasing new models in The Haunted Busts throughout the season. A few community verbatims…

• “This has got to be my favorite thing I've ever printed by far."
• “This is unbelievable.”
• “Man this is sick!”

See for Yourself

Featured on the Action Lab

Featured at timestamps 4:15 & 6:53 in the video above.

How to Print

• You can't go wrong with basic white PLA. Alternatively, glow green looks ghostly.
• My filament settings disable the aux fan. If you switch settings, I strongly suggest re-disabling that fan.
• I painted in minimal supports to prevent excessive wobbling, but all supports are disabled on the lamp versions which wobble less. Steep overhangs won't be perfect but aren't very noticeable when displaying. You might have to cut off a few loose strands on the underside of the top. Adding more supports for perfect overhangs would significantly increase the time & material requirements. I didn't find the tradeoff worthwhile, but you do you.

How to Display

• Concave (hollow) side faces the viewer. Place near head height.
• Best viewed from 8+ feet away where binocular vision becomes less effective.
• Light from underneath for the best effect.
  • Direct underlighting is the easiest way to get a great effect, like a holographic projection that stares at you. I suggest one of the Lamp print profiles since they position the light for you. They're compatible with the Bambu LED Lamp Kit (see Bill of Materials for link). While it's the most convenient/integrated option, pretty much any light you can put near the bottom will work.
  • Upwards-angled lighting from a few feet in front yields a more life-like effect.
  • If using glow PLA, it's best to “charge” from directly in front or behind so the glow will be even. That said, I find that the glow models still look best when being actively lit from underneath, rather than when in glow-in-the-dark mode.

If you're wondering how this works, it's because inverting a face's geometry swaps which parts are light / which are dark. Underlighting also swaps light / dark, and this double-reversal makes the figure look like a naturally lit convex face. This geometric interpretation is strengthened by the fact that most humans are hardwired to recognize faces as being convex. When you move, however, the image you see from the inverted face changes differently than how your brain expects a convex face to behave. To reconcile the discrepancy, your brain interprets the figure as turning.

Thank You

Finally, a big thanks to Cody Raskin who created the original Lincoln bust model.

Enter the Next Dimension (Easy to print. Lit by a glow stick. Free.)