Snap-On Fixed-End Hanging Pendulum Filament Guide

Snap-On Remix for Fixed-End Spool Holders

A snap-on remix of David D.'s Hanging (Pendulum) Filament Guide, a weighted arm that hangs on your spool holder and keeps light tension on the filament path from external spools, so the line can’t drift off the spool and tangle. His original closed eyelet is the right design when you can slide it onto the rod from one end, and it comes in three eyelet sizes (26, 36, and 46mm). If your spool rod is removable, go print his version. But some holders have fixed ends with flares or caps, like the Bambu X2D stock top mount, and nothing threads onto those. This version converts the 26mm eyelet to a C-clip that snaps onto the holder radially and stays put.

The Engineering

The opening size is not a guess. The gap is a 90 degree segment sized from bending strain math for a C-ring flexing over a 26mm shaft. Peak strain during snap-on lands around 1.4 percent, comfortably inside PETG’s working limit. Rounded entry bulbs on the tips guide the shaft in and spread the ring smoothly. The gap is also rotated 60 degrees off the arm centerline, so the load path never rests on the opening. It goes on with a firm push, a positive click, and swings freely as a pendulum. Tested on an X2D stock top holder and others (as seen in the photos) in PETG HF.

Bonus: Light Spool Keeper

Many fixed-end holders are graduated, widening toward the flared end. Because this clip fits snugly instead of loosely, it doubles as a spool keeper: it blocks the spool from walking outward off the end while still penduluming freely guiding your filament with ease.

Material Matters

Print this in PETG, ASA, or ABS. The snap fit depends on flex. PLA has roughly half the strain tolerance, so it will probably survive a couple installations, but repeated cycles with PLA will likely cause stress cracking, and matte PLA is  even worse. I haven't tested PLA to failure on this, so YMMV, but I'd just use PETG or something with better strength and flex than PLA.

⚠️ IMPORTANT PRINT NOTE

Use 4 or more wall loops (the profile has this set). The ring works as a spring and needs solid perimeters in the bending section, not sparse infill. Everything else stays at defaults. The plate includes mirrored left and right arms, plus the original design’s small locking pins as an optional backup if the detents ever wear. The original designer reports the detents holding fine on their own and that has been true for me as well, but they're there if you need them.