DIY Hologram Pyramid: Cut One to Fit Your Screen
A hologram pyramid is four panels of clear plastic taped into an upside-down, flat-topped pyramid that stands on a phone or tablet. HoloPath exists because of one: it was built for a STEM project that turned Magna-Tiles into a hologram projector, written up on Substack. This guide gives you the measurements for your own screen, worked out so the pyramid matches the layout HoloPath produces.
What you need
- Clear plastic sheet: overhead-projector film, a clear plastic folder, or the lid of a CD case. Thin film flexes but gives the cleanest single image; a CD lid is stiff but thicker, so it shows a faint double image.
- A ruler, a fine marker and a craft knife or sharp scissors.
- Clear tape.
Skip glass: it is hard to cut accurately and dangerous to handle as small panels. Skip frosted or tinted plastic, which kills the reflection.
The shape of each panel
Each of the four panels is a trapezoid: a long bottom edge, a short top edge and two slanted sides. In use the pyramid stands on its short end, and the faces lean out at 45°. Three measurements define it:
- Base (B), the long edge.
- Top (T), the short edge, which becomes the square opening that sits on the screen.
- Panel height (H), measured straight up the middle of the panel.
For the faces to sit at exactly 45°, the panel height and the slanted sides follow from the other two:
slanted side = 0.866 × (B − T)
The well-known template of a 60 mm base, 10 mm top and 35 mm height is this rule at work: 0.707 × 50 = 35.4.
Sizing it to HoloPath's layout
HoloPath's four-sided layout leaves 3% of the screen empty at each edge, then draws each copy almost to the centre, stopping about 5.6% of the screen's width short of it. A pixel's distance from the centre becomes its height in the floating image, so the pyramid has to cover that whole band:
- make the base about 95% of your screen's short side, no less than 94%;
- make the top about 11% of it, no more than 11.3%.
A smaller base cuts off the top of the hologram; a wider top opening cuts off its feet. Measure the screen's short side across the lit area only, not the bezel, because a square GIF played full screen fills exactly that width.
| Screen's short side | Base | Top | Panel height | Slanted side |
|---|---|---|---|---|
| 65 mm (typical phone) | 62 mm | 7 mm | 38.9 mm | 47.6 mm |
| 150 mm (small tablet) | 143 mm | 16 mm | 89.8 mm | 110.0 mm |
The phone pyramid makes a hologram about 27 mm tall; the tablet one, about 62 mm.
Cutting and assembly
- Draw one trapezoid on paper first and check it against the formula: if the slanted sides come out shorter or longer than 0.866 × (B − T), the faces will not sit at 45°.
- Trace four copies onto the plastic. Score film or a CD lid with a knife along a ruler and snap it, or cut film with scissors in one smooth stroke. Matching panels matter more than perfect edges.
- Tape the slanted sides together on the outside only. Tape on the inside faces shows up in the reflection.
- Check that the top opening is square and the pyramid stands without rocking.
Using it
Make the hologram in HoloPath with the Pyramid 360° layout, which places four mirrored copies with their bases pointing at the centre. Play it full screen at maximum brightness, with auto-brightness off, in a dark room. Stand the pyramid on its small end in the middle of the screen, with its sides parallel to the screen edges, and look straight in at the height of its middle.
When it does not look right
- A faint second image beside the first. Both surfaces of the plastic reflect. Use thinner sheet.
- One pair of opposite faces is much dimmer. Your screen's light is polarised, and a face reflects one polarisation ten times better than the other. Turn the phone through 90° to swap the dim pair; the optics article explains why.
- The image tilts or sits too high or too low. The faces are not at 45°. Re-check the panel height against the formula.
- The feet or the top of the hologram are missing. The opening is too wide or the base too small for the layout; see the sizing rules above.
- Text reads backwards. The file was made with a layout that is not mirrored, such as Single Image. Use Pyramid 360°.