Engineers understand how to design strong yet light beams by putting the strong material toward the outside edges of a cross-section and filling the inside with lighter, weaker material.
Wahandisi wanaelewa jinsi ya kubuni sana lakini katika mwanga mihimili kwa kuweka vifaa kali katika pembe ya nje ya sehemu ya msalaba- na kujaza ndani na nyepesi, na nguvu nyenzo.