Powder-coated aluminum shrugs off rust, recycled polypropylene stays light, and breathable fabric pots air-prune roots yet fold flat. Balance durability, UV resistance, and touchable warmth. If you must choose, prioritize weight and grip; stairwells are less forgiving than catalog photos promise.
Quick-release clips, stainless carabiners, and Velcro wraps let modules snap apart fast yet hold steady during gusts. Color-code segments for herbs, flowers, and tools. Test every joint by gently shaking; if it rattles now, a storm will find the weakness later.
A full kit simplifies choices, but hybrids unlock flexibility: milk crates with food-safe liners, bamboo shelves on sliders, and rail brackets paired with tote bins. Measure compatibility carefully, then record sources, screws, and spacers so you can re-order replacements after moving.