Why a 3D-printed part can be strong in one direction and weak in another — and a machined aluminum bracket usually can't.
Ask for "the strength" of a material and most people expect a single number back. For a lot of engineering metals, that instinct is basically fine. For wood, fiber composites, and — increasingly relevant — additively manufactured (3D-printed) parts, it can be badly wrong. Some materials genuinely behave differently depending on which direction you load them in, and treating a direction-dependent material as if it had one universal strength number is one of the more consequential and avoidable design mistakes in modern manufacturing.