Solution to Challenge 3

Planning
Running the script with 12 units and 4 colours gives 12 // 4 = 3 units of each colour.

Building
1. Fold 3 units in each of the four colours, 12 in total, and compare them to your best unit.
2. Join all units loosely first, following a repeating colour order.
3. Tighten the connections in a second pass.

Keeping tension even
- Join loosely, then tighten, so no connection is forced early.
- Re-fold any unit that looks short or has soft creases.
- Check the model all the way round before the final tightening.

Checkpoint: three units of each colour, a symmetrical model, and no glue needed.