Modular Filament Shelf (21-31 mm dowels)

All the filament-spool shelves I found on MakerWorld were either too weak or didn’t have the right hole size for my dowels, so I designed my own—super-strong and available in several sizes so anyone can use it.

The design is inspired by the popular “filament spool shelf honeycomb”, but flipped upside down. That makes it more compact and stops the end spools from tipping over. The beefier construction also lets you use thicker dowels, so a wide shelf can hang from just two anchor points. My own shelf, using 27 mm dowels, is 120 cm wide and fits about 17 spools of filament.

The model is available in six sizes: 21, 23, 25, 27, 29 and 31 mm. The number is the wooden-dowel diameter. Each model has a 1 mm margin, so a 21 mm file will still fit a dowel that actually measures 21.2 mm. A dowel 1 mm under nominal also sits snugly.

The ends feature small stops that keep the dowels from sliding out while improving the shelf’s appearance. There are two different end plates—one left, one right—and they’re not interchangeable, so print one of each. If you need a third anchoring point for an even wider shelf an optional extender shelf without a stop is included.

Print in PETG (recommended) or PLA. The print profiles use the bambu “0.20mm Strength” settings but if you want to save material you can switch to “0.20mm Standard”

Assembly

I used two 6 × 80 mm lag screws and 8 mm plastic plugs to mount my shelf. For the hole i used a 7.5 mm drill (7 mm works  too if you wiggle it to open the hole slightly). You don’t have to use lag screws—a normal flat-head screw works too. I strongly recommend using plugs. I used this setup in lightweight concrete and i seem to have no problem when loading the shelf with ~ 20kg. The distance between the holes is 158.29mm (see drawing).

Note: Mount one end of the shelf first, insert the dowels, and then mount the other end (the stops mean you can’t add the dowels afterward).

Drawing: