I snagged a few 20mm outer diameter, 2mm wall‑thickness PVC water pipes from my Taobao 88VIP red envelope and initially planned to craft a stackable storage box out of them. But after realizing how haphazardly my filament was scattered around, I decided to start with a filament rack instead.

Drawing inspiration from the Hai Feng Li Zi’s Thread Holder – Filament Rack – Stackable Design, I sketched out my own version.

• To accommodate nylon cable ties for secure fastening or future expansion, I added two 6mm‑diameter holes to the design.
• To prevent the two PVC pipes from bending under the weight of the filament, I modeled a stabilizing ring to keep them firmly in place.
• The original designer recommended keeping each layer of PVC pipe no longer than 50 cm—this worked well in practice, but it didn’t quite align with the 60 cm depth of my existing shelving unit. To address this, I designed a straight-through connector that allows me to add an extra 10 cm of PVC pipe, bringing the total length up to 60 cm. This way, the side posts of the shelf can serve as supportive anchors, further enhancing the stability of the filament rack.

• PS:If there are tolerances in the connectors, you can wrap them with ultra‑thin 0.1 mm PVC electrical insulation tape or PTFE tape—depending on the inner diameters of the PVC pipes you’ve sourced. The exact number of wraps will depend on whether the pipes slide in and out smoothly after insertion.

I recommend building no more than 8 layers; taller racks become less convenient to access and store items in. Use 6 mm wide nylon cable ties to secure the brackets between each layer.

For printing, plan for 2 brackets per layer.

For designs with fewer than 4 layers, 2 walls, 5 top surfaces, 3 bottom surfaces, and 15% infill should suffice.

When building racks with more than 4 layers, reinforce the lower brackets by increasing the number of walls to 4, adding 5 top surfaces and 5 bottom surfaces, while maintaining 15% infill—and feel free to adjust the infill percentage slightly higher if needed to ensure structural integrity.

STEP files are now available; feel free to modify them according to your specific tolerances!