Triangular Lantern - LED ONLY
One-piece triangular prism lantern with three open windows, integral frame, triangular floor and glue tabs. Open top for a battery LED.
Materials
- 180-220 gsm cardstock
- Scissors
- Craft knife and cutting mat (adult use)
- Ruler and blunt scoring tool
- PVA craft glue
- Small cool-running battery LED, maximum 26 mm diameter x 30 mm high
Finished size: 54 x 46.77 x 110 mm (equilateral 54 mm sides)
Steps
CutValley foldMountain foldGlue area
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Check scale and identify the net
Print at 100% actual size. Measure the 50 mm ruler before cutting. P1 has three 54 x 110 mm wall panels in a row, a triangular floor below the left panel, two 6 mm floor tabs, and an 8 mm seam tab at the far right.
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Score and cut
On a mat, lightly score all six dash-dot fold lines with a ruler and blunt tool. Cut out the three 34 x 76 mm window holes first, then the outer perimeter. Keep the narrow rails and every tab intact; do not cut fold lines.
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Pre-fold with print outside
Keep the printed face on the outside of the finished lantern. Mountain-fold the two full-height wall creases 120 degrees from flat, leaving 60-degree interior corners. Fold the right seam tab another 120 degrees from its wall so it will lie behind the leftmost panel. Do not glue yet.
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Form the integral floor
Fold the triangular floor inward 90 degrees from its wall; its printed face will point down. Fold both 6 mm floor tabs up 90 degrees from the floor, with printed glue faces pointing outward toward the walls. Dry-fit all three walls around the 54 mm floor edges.
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Glue the floor tabs
Open the side seam for access. Spread a thin film of PVA on the printed faces of both floor tabs. Wrap the middle and right walls around them; align wall bottom edges flush with the floor. Press each tab against the inside of its 20 mm bottom rail, using a fingertip through a window. Hold 60 seconds or until the glue grips; keep the floor level.
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Close the vertical seam
Apply PVA to the printed face of the 8 mm seam tab. Tuck it behind the free left edge of the first wall: the full overlap stays inside its 10 mm side rail. Match the top and bottom edges to make a 110 mm tall prism. Pinch through the adjacent windows until set. Leave upright for 30 minutes or the glue maker's full drying time, whichever is longer.
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Insert LED through the open top
LED ONLY - never flame. Use a cool-running battery LED no larger than 26 mm diameter and 30 mm high; a normal 38 mm tealight will not fit. The triangular opening has a 31.18 mm inscribed circle before paper thickness. Switch the LED on outside, lower it through the open top, and center it on the floor. Retrieve through the top, using a window to guide it if needed. Keep upright on a flat surface and lift by the base, not the window rails.
Notes
The 3D model shows each piece in its finished, idealized shape; the exploded view only spreads the pieces apart. It is not a paper-physics simulation: curved shapes are forming guides, not exact physical folding or proof of developability, and intermediate fold shapes are not supplied.
- LED ONLY. Never use a candle, flame, incense or hot lamp inside this paper lantern.
- Original one-piece net: three 34 x 76 mm cut-out windows; 10 mm side rails, 20 mm bottom rails and 14 mm top rails. The top stays completely open.
- Exact piecewise-rigid net and 3D correspondence, including every tab. Paper thickness and glue films are not simulated; glued surfaces coincide in 3D.
- Use as a tabletop decoration, not a hanging lantern. LED is a purchased accessory and is not shown as paper geometry. No window film or hidden supports required.
- Physical printing, cutting, folding, seam fit and LED stability remain pending. The step viewer shows final part placement, not continuous folding.