Stackable Filament Spool Holder, 1/4" / 6mm dowels

Note: I don't recommend you build this one, it's too wobbly.  My 10mm dowel version here is much better.

Stackable spool holder using 12" bamboo dowels I got off Amazon.  The dowels were supposed to be ¼" but there was a good bit of dimensional variation and most were around 6-6.2mm so this didn't entirely work out.  Parameterized F3D included if you need to tweak dowel size, or 

Each level holds 4 1kg, 200mm spools.  With two layers it's pretty wobbly when actually messing with the spools but is sturdier than it looks.  It's meant that you could keep adding layers but I'm not sure I would, it would probably need to be remixed with ½" dowels or just made out of firmer stuff..