I mounted my FilaWinder vertically, and am using large spools (two normal 1kg spools with the ends cut off and glued together) so I needed an arm that was stronger than the stock piece, and could fit a slightly wider spool. This arm doubles the 'beef' of the hinge, and moves the pivot point out an extra inch or so. This also clears up the interference between the pivot point and the mounting screw in the original.
Drawn in DesignSpark Mechanical, editable RSDOC file is included.
The upgraded motor mount/arm from DataSmasher is also in the RSDOC file... I intend to incorporate it into a beefier design of the whole thing, but haven't done anything with that part of it yet. No STLs for that one, just figured I'd credit the origin of the file if anyone noticed it in the RSDOC.