Printrbot Simple Metal Feeder Tentacle

See it in action here: https://goo.gl/gv60W8

This is a neat little doodad for attaching to the filament feeder of a 3D printer. As the filament is fed to the extruder it will spin. You can tell at a glance that your filament is extruding or retracting properly. There are 2 versions: a tight gap and big gap. The tight gap is just big enough to fit snugly. It SHOULD stay on with merely friction. However if you don't want to risk it falling off, get the big gap tentacle. There's a little