Triangle-based pyramids consist of four flat triangles, at least three of which must have identical dimensions. Usually all four sides are identical equilateral triangles. The exact process for making a pyramid varies according to the materials, but a basic design works well with any flat medium such as card, sheet metal, wood or modelling clay. The procedure requires concentration and the accurate use of a rule and cutting tools.
- Skill level:
Things you need
- Stiff cardboard
- Scissors or craft knife
- Measuring rule
- Pair of compasses
Decide on the size of the pyramid base. The base is a triangle with all three sides the same length. Draw a straight line, the length of a triangle side, about one centimetre in from the edge of a sheet of stiff card.
Insert a pencil into a pair of compasses and set them so the distance from the pencil tip to the pivot spike is the same as the length of the line drawn on the paper. Place the pivot point on the left end of the line, with the pencil tip at the right-hand end of the line, and draw an arc from right to left. The line will curve over the top of the straight line.
Reposition the compasses so the pivot point is resting on the right-hand end of the straight line, with the pencil point resting on the left-hand end. Draw an arc from left to right, moving over the top of the line and crossing the arc drawn in Step 2.
Draw straight lines from the point where the two arcs intercept above the line to each end of the line. This creates an equal-sided triangle. Create three more triangles using the same process, or use the first triangle as a template and draw around it.
Cut around three of the triangles, leaving 1cm of extra material outside the line on the left-hand side and at the base. The extra material is for folding over as flaps to glue the pyramid together. At each corner of the triangle, trim away the surplus material to produce a flat edge instead of a point. Do this so the cut just touches the top of the drawn triangle. Cut the fourth triangle exactly to the lines, leaving no flaps. This is the base triangle.
Score along the drawn lines between the triangles and the flaps by placing a rule along the line and running the back of the scissor blade along the line. Bend the flaps inward to create raised sides like the edges of a tray. Do this to all the triangles with flaps.
Place the base triangle on a flat surface. Apply glue to one flap on another triangle and press it firmly onto the base triangle so it matches the edge of one side of the base. When the glue is set, apply glue to the base and side flaps of the next triangle. Stick it to the right of the first triangle, aligning it carefully with the existing side and base. Repeat with the third triangle, applying glue to all the remaining exposed flaps. Allow to dry.
Tips and warnings
- Thin paper will lose its straight sides if you make the pyramid too large, so use the stiffest material you can find.
- Care and precision in marking out and cutting make the final assembly much neater.
- Keep glue away from surfaces other than those being bonded.
- Don't use a craft knife unless you have protected the work surface beneath.
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