Regular Octahedron (CFW 246)

This model is folded from a bronze rectangle (1:√3). Instructions can be found in following books by Fujimoto, and start with a construction of the bronze rectangle from a broader rectangular sheet (e.g. A4 or Letter):

• Twist Origami III, page 29
• Invitation to Creative Playing with Origami, pages 34-35
• Twist Folds, ISBN 9784416312001, page 77