Rack ^ shelf .. (jargon file) Barebone racks use nothing but metal bars like Omar and the first ikea railroad. Some racks (like Hyllis) add planks  and I still call them racks. However, when the vertical parts become walls, then I call the structure a shelve including most of wife’s purchases.

A Pigeonhole is defined as a compartment having 5 walls. Majority of the shelves feature pigeonholes including grandpa’s bookshelves.

— framework: my preferred storage types in practice 👍 👎

• #1 open rack holding transparent trays or boxes .. usually more convenient than bags, in terms of payload access.. no need to open the bag and later close it.
• ..less flexible compared to hanging bags esp. in terms of level adjustment, but on a given shelf, we can squeeze many items or space them out. In this way, it’s more flexible than pigeonholes or drawers
• #2 transparent bags (of various sizes) hanging on a rack .. inexpensive, zero set-up, highly flexible and versatile. I relied on this single solution for decades, esp. in tiny rooms. The more luxury residences [all the furniture wife bought] tend to feature fewer racks and more drawers or pigeonholes, so hanging spots are fewer. I always spend some time locating (or creating) them. For wood furniture, I can also screw on hooks but it would leave a hole in the wood.

1) racks and 2) hanging clear bags [incl magazine bag] offer better visibility and flexibility than 3)pigeonhole bins (possibly with glass door) or 9) very worst visibility: drawers or pigeonholes behind doors.

Drawers breed the horrible habit of “piling up”… buried items suffer poor visibility. I never like deep drawers.

— wood shelves in general

• 🙁 🙁 water damage … shorter lifespan than plastic or (some) metal. Once we accept 1~2Y “discard”, we can still use cheap shelves in wet areas.
• 🙁 crack … if screwing at wrong part of the the wood, or wood piece receiving oversized impact
• 🙁 tends to have fewer gaps/holes for hooks. In contrast, metal racks tend to have many, esp. Omar
• 🙁 [assuming the same rough handling] majority of wood racks are less durable than metal racks. Note wood racks are inexpensive and seldom use hard wood.

— metal shelves in general

• 🙁 🙁 hard to screw on stuff. Need to drill hole using metal drill bit
• .. need to exploit all existing screw holes .. like fixing a hook array. Those metal racks with plenty of holes are precious
• 🙁 less versatile, less presentable for the living room or bedroom
• 🙁 can’t put on glider easily. Need to put on plastic “shoe” first

— the Omar rack

• Indoor moisture ok, but too much moisture (rain + communal wash) would tarnish its appearance. Better cover with some plastic sheets, tied to the top
• Luckily, the transportation and construction legwork is nice, so I could buy a replacement (before Omar is discontinued), and reuse some old shelves.

— the big brown rack

• MWLR [meta/wood legacy rack]
• 🙂 longer than most single racks
• .. 👎 therefore heavy.. harder to move
• height adjustable, but only four levels. The vertical size is rather large with high visibility, so we get some “desktops”
• 🙂 metal structure can fit my ikea bracket but not as tight as in new ikea designs.
• 👎 wood can get wet