Maker Tips

How to Create a Supported Shelf with Triangle Fold

30-60m
Ages Years 3-6

Ready to engineer with triangles?

A triangle shelf might look simple, but its shape does a lot of heavy lifting. With a few quick folds the flat cardboard becomes a triangular supporting shelf that resists sagging and holds its form over time.

Discover why engineers rely on this simple yet powerful shape in bridges, buildings, and everyday structures.

Download and print this template for makers!

Follow the Template

Step 1

Determine window and shelf location: Using an assembled medium-sized box, have students decide where a good window display would be.

Follow the template: Use the Makedo Fold-Roller to mark cuts and folds to create a supported shelf with a triangular fold integrated into a cardboard box. 

Cut top and sides only

Step 2

Use the Safe-Saw to cut the top and sides only.

Fold

Step 3

Bend down at Fold 1.

Step 4

Bend down at Fold 2.

Step 5

Bend in at Fold 3 (note, this fold is in the opposite direction from folds 1 and 2).

Connect

Step 6

Hold in position and connect flap C with a Scru using a Scru-Driver or Mini-Tool.

Master Moves

Stability Tips

  • Flutes: The shelf works best with flutes running vertically (perpendicular to the fold lines). If the flutes are inline with the fold, stability will be lost when pressure or weight is added to the shelf.
    You can test stability by building one shelf with flutes running vertically and another with flutes running horizontally, and compare how well each version supports weight.

  • Angles: A strong shelf can be made using a right isosceles triangle as the support. This means two sides are equal in length, with a longer side joining them. Imagine the shape you get if you take a square and draw a line from corner to corner.

To calculate the length of the longer side "B", we use the equation A x √2.

  • A simpler way to see this is:
    A x 1.41 = B

  • For example, if A = 10cm, our equation would be:
    10 x 1.41 = 14.1cm

Note: Make sure Flap C is a minimum of 4cm. This will allow enough space to connect the support with a Scru.

Option to Hide

If there is limited space to connect the folded flap, you can conceal it by folding it up and under rather than down. Then, use a Scru from the inside out to connect the shelf to the structure.