This device allows you to store and use lengths of 1.75mm filament for a 3D pen. The unique mini spool is designed to prevent the filament from unraveling under its own spring tension. The parts can be welded together with your 3D pen.
I designed a spool holder that clips onto my generic 3D pen. I invite owners of other 3D pens to design their own spool holders and post them here as remixes.