I’d call this the most user-friendly in-car (air-conditioning duct hook) phone holder:

The file also includes a custom-made backplate for the phone holder.

1. No supports, no skirt, and no overhangs are required during printing, saving both time and material.

    

2. Only 10–15% infill is needed for PETG or ABS, and a 30% infill density is sufficient where you need to tighten screws (M2.5×8 or M2.5×6).

    

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3. Printing on a flat surface makes the printed structure more stable. For certain parts, printing at a 45-degree angle can provide extra strength, but it will generate a small amount of support material.

   

   Of course, if the filament is strong enough and you use plenty of material, there’s no need to worry about the challenges of flat-bed printing.

    

    

4. The air duct hook is designed for 44-mm-thick air-conditioning duct blades; it fits snugly, with spaced mounting holes so you can adjust the tension as needed.

    

5. Assembly requires no glue—simply thread the filament through the designated slots to secure the bracket and tighten the hook.

    

6. Disassembly and storage are both convenient.

    

    

   Assembly instructions (please read carefully and pay attention to installation details):

   1. Following the diagram, insert the filament at points A and B without cutting it at point C, then slide the hook into the air duct.

    

   1. The filament is inserted at point A to allow the hook to reach its maximum insertion depth.
   2. The filament is inserted at point B to secure the hook and prevent it from wobbling.

    

   

    

   2. Press down on D (the air-conditioning duct blade) to push it upward and press the hook’s thin plate against the blade.

      Pull the thin plate outward to ensure the hook adheres tightly to the duct blade.

   

    

   3. First cut the filament so that it is flush with the hole, making it easier to insert the clip on the support base.

   

    

   4. Insert the bracket rod into the hole on the support base; this may take a bit of time and patience to get the position right, since you can’t see the back side.  

      You can reduce the outer contour of the hook’s thin plate by -0.2 (the file uses -0.15), which will make insertion even easier.

   

    

   5. Prepare a piece of nano tape (which won’t leave residue when peeled off). Alternatively, you can use foam pads, silicone pads, or other non-smooth padding materials to increase friction between the support base and the car’s surface.

   

    

   6. Apply nano tape to the support base, then roughly position it on the car’s surface (before applying the nano tape, arrange the position, place the phone to test the range of motion, and finalize the placement F).

    

   G: Reinsert the filament (just bend it slightly up and down for easy future removal—don’t cut it short, to prevent it from falling out over time), lock the support base in place, tighten the hook, and complete the final installation!!

   

    

   Finally, thank you for your patience in reading this guide, and we wish you successful printing and happy use!!