This is my take on a Modular Spool Rack. After I could not find an existing model that did everything I wanted, I designed my own.

Here are the key features:

• modules can be printed as is - no assembly required
• easy print - no supports needed
• can print two modules at once on an A1 sized print bed
• modules are connected by dovetail interfaces (in all 4 directions)
• can be clamped to a table with the provided table clamp (to prevent tipping over)
• can attach Honeycomb Storage Wall segments to the sides
• quite strong for the amount of filament used
• indents at the bottom to prevent the spools from rolling out
• extendable - you can create your own extension for the different attachment points

Check out the MSR Collection, where I will add all my attachments for this project.

It's meant to hold Bamboo spools (and others of the same size) and refill boxes. I decided against allowing boxes with spools inside to save some filament (and I don't usually order those boxes anymore). I will probably add a bigger version in the near future though, in case someone else wants that.
The model won't fit on the A1 Mini.

I recommend using a 0.8mm nozzle for faster print times. I will also add profiles for 0.4mm, in case you don't have any other nozzles.

Recommended print settings

I already have some more stuff for this system, that I want to upload here as well, as soon as I find the time.
Feel free to ask, modify or give feedback. I also provided some basic drawings with the most important measurements in the pictures section.