Solution to Challenge 2

Building the cube
1. Fold six identical units, two in each of three colours.
2. Join two units by sliding a tab into a pocket, then add a third unit to make one corner.
3. Add the other three units one at a time, tucking each tab into the nearest free pocket, without pushing them fully home.
4. When all six units are in place, tighten each connection and square the edges.

Checking the result
- Opposite faces should be the same colour. If two neighbours match, swap one unit.
- The cube should hold without glue.

If a unit slips
- The unit is probably shorter or looser than the others. Re-fold it with sharper creases, or use slightly thicker paper.

Checkpoint: six faces, three colour pairs, and a cube that keeps its shape when handled.