Zippy - The Symmetrical Filament-Rider Cable Trolley

Meet Zippy, an ultra-lightweight, smooth-rolling trolley designed to travel along a unique track: a taut strand of 3D printer TPU filament! Instead of requiring bulky ropes or expensive steel cables, Zippy is engineered to use standard flexible filament as its guide wire. The inherent high friction and flexibility of the TPU line give the trolley incredible grip, silent operation, and zero slippage, making it an excellent choice for mini camera sliders, desktop automation, or lightweight rigging experiments.

🔄 Fully Symmetrical Design

Zippy features a completely symmetrical chassis equipped with integrated V-groove wheels to perfectly cradle the filament track. Because it is uniform from top to bottom, the trolley can easily be flipped upside down depending on your mounting needs. Use the integrated lower side openings to tie off a suspended load, or print your own custom counterweight to keep the rig balanced and stable during transit.

It utilizes standard, easy-to-source skate bearings and basic metric hardware.

🛠️ Hardware Required

To assemble one Zippy trolley, you will need:

• 4x Standard Skate Bearings (608-2RS or 608-ZZ, 8x22x7mm)
• 4x M3 Screws (Length: [Insert your length, e.g., 12mm - 16mm])
• Track: A strand of TPU filament (1.75mm or 2.85mm) stretched taut between two anchor points.

🖨️ Print Settings

• Material: [Insert material, e.g., PLA / PETG / ABS] – The trolley body and V-groove wheels can be printed in a rigid material since it runs directly on the flexible TPU filament wire!
• Infill: 20-30% (Grid or Gyroid recommended for structural rigidity).
• Walls/Perimeters: 3-4 perimeters to ensure the bearing posts, V-grooves, and lower tie-off openings are solid.
• Supports: [Mention "None" or "Minimal" depending on your model's orientation]

🔧 Assembly & Setup

1. Press-fit the 4 skate bearings into their designated V-groove wheel slots on the chassis.
2. Secure the wheels/bearings using the 4 M3 screws. Ensure they spin perfectly freely without binding.
3. String your strand of TPU filament through the center tracking groove between the V-wheels.
4. Anchor and tension the TPU filament until it is straight and taut.
5. Rig your payload: either print a matching counterweight or use the lower side openings to tie on your load, place Zippy on the line, and watch it glide!