This Gridfinity based spool holder can be used by itself on the shelf or as part of Gridfinity  layout. 

It works well with my shelf topper to stage common colors or items queued up to be added to the AMS. 

Full size and smaller sized spools fit well.

The radius and perimeter depth allow stacking when empty. 

There are three evenly spaced grooves which fit these mini spools when empty.

[https://makerworld.com/en/models/906112-bambu-spool-mini-a-small-spool-for-waste-filament#profileId-1658062](https://makerworld.com/en/models/906112-bambu-spool-mini-a-small-spool-for-waste-filament#profileId-1658062)

See my Gridfinity collection.