Each iteration of A-sized paper decreases in area by half, (so the side lengths decrease by a factor of 1/(sqrt2)): A5 is half the area of A4, A6 half the area of A5, and so on. So the base of an A6 tetrahedron is a quarter the area of an A4 base, meaning that four A6 tetrahedron bases can be packaged in the gap left by an A4 tetrahedron. I played around and found some other combinations (see some examples below).
- Tetrahedron net with tabs - SEN Teacher does one here.
- Different coloured card
- Ballpoint pen for scoring the card
- Backing paper or ready-made canvases