This is a modular holder for the filament - you can place a spool with the filament in it. It has a simple swing mechanism for getting the spool out using your hand or leg or whatever comes to your mind - just press down and the spool is extracted. You can connect the holder in series - there are connectors included.
Basically you need either one file:

• Filament Holder v.3 - ALL-IN-ONE - FLAT.stl

Or two files, if you don't want the parts over each other:

• Filament Holder v.3 - ALL-IN-ONE - FLAT - NO SIDES.stl
• Filament Holder v.3 - ALL-IN-ONE - FLAT - SIDES.stl

Other files are there if you'd need the - for example, if broken or I don't know... :-)

Is this the most practical filament holder? I doubt. Why did I design it? I want to get a spool quickly by pressing with my foot on the pedal and to be able to see my filament in nice rows - under the 3D printer table. I hope You enjoy that - leave a comment if You have any questions!