Line spooler that clamps to the rail
Holds the spool at the right angle with an adjustable brake, so line lays evenly without twist.
The problem
Spooling new line alone usually ends with someone holding the spool on a pencil. The line twists, and you notice on the first cast.
The fix
The clamp fits on a rail or a table edge. A printed shaft with a felt washer gives adjustable friction, and the arm angles so line feeds straight onto the reel.
A simple part, but it solves a problem everyone has had. It sits in the queue behind the parts that need finishing first.
More ideas
A hook guard that actually stays on
A soft TPU clip that snaps over treble hooks and jigs so they stop catching nets, clothing and fingers.
A rod holder that fits your rail
A parametric holder printed for the exact tube diameter your boat has — not a standard no boat actually follows.
Gear tags for nets and pots that last
Name, phone number and registration embossed into the tag itself — not written in marker that vanishes in three weeks.