A hologram you can reach for

I made this box in early March 2026 as my final piece for the Immersive elective at Nimeto Utrecht. I wanted a hologram that works without a phone and reacts to whoever is looking at it.

How it works

The box uses Pepper’s ghost, a 19th-century stage trick rather than a true hologram. A small square display lies flat in the bottom, facing up. Above it, a clear plate at 45 degrees reflects the screen toward you. Because the inside of the box is dark, only the bright image shows: a sphere of light-blue particles that seems to hang in mid-air. Everything on the screen is drawn mirrored, so text reads correctly after the reflection.

A Raspberry Pi drives the display and runs the software, and a webcam on top of the box looks at the viewer. The tracking finds your hand as a skeleton of 21 points, and the particle sphere responds to how your hand moves.

How I made it

I designed the box around the display and laser-cut it from plywood, with a slot in the side wall for the HDMI and power cables. While testing I held the panels together with masking tape, so the build stayed easy to adjust.

On the morning of the build day the screen still showed the standard Raspberry Pi desktop inside a bare wooden box. By the afternoon the particle visual was running and the inside was dark, because the reflection only reads as floating against a dark background.

What I learned

The illusion depends on contrast more than on hardware: a dark lining, a black background and bright particles do most of the work. Hand tracking changed the piece the most, turning a screen trick into an object that responds to you.