This serves as a bumber for the spool and the Printrbot Aluminum spool rack so that a spool cannot get caught on the screws that mount the rack to the handle (which could cause printing problems).
- Print the Spool Guide.
- Slide it on the the rack (with hook down)
- Align the holes with the heads of the screws.
- Press firmly on the hook until it pops and latches around the rack