Low-Profile AMPS (30x38mm) Swivel Mount/Adapter

A low-profile ball and socket swivel mount/adapter using the standard AMPS 30 × 38 mm hole pattern, designed for phone mounts, GPS units, small displays, cameras, and similar accessories.  Compatible with RAM-style, Magsafe, Garmin, ProClip, Bulletpoint, Scosche, and other mounts that use the AMPS hole pattern.  

The print profile includes versions with simple through-holes for M4 hardware, versions with M4 nut traps/inserts, and versions for self-tapping screws.  Mix and match as needed.  The top plate has been oriented vertically in the print profile to increase strength in the center post, which might otherwise be vulnerable to breakage.  A small and easily-removed support is needed on the center post, but no brim is needed for the top plate.

• AMPS 30 × 38 mm hole pattern
• Minimal stack height
• Tool-free assembly and disassembly
• Hand-tightens securely

Assembly / Adjustment

1. Refer to diagrams for the arrangement of parts.
2. Test fit the threaded parts and run them up and down a couple times to smooth the threads.
3. Place the compression nut over the center post on the top plate with the open side of the nut facing out (refer to drawing).
4. Thread the ball onto the center post, capturing the compression nut on the top plate.  Tighten firmly by hand.  Optionally, apply a small amount of superglue to secure the ball onto the center post (keeps it from accidentally unscrewing later).
5. Screw the compression nut into the bottom plate to attach the top and bottom plates.
6. Tighten by hand to lock the angle.

Bambu Lab PETG HF has performed the best for me, producing very smooth threads and a firm, consistent ball-and-socket connection. I also tested several other PETG and PCTG materials; most of them produced noticeably squeaky or gritty threads and joint movement, making it harder to tighten the compression nut.  Matte PETG and matte PCTG materials were better than their glossy counterparts.  I didn't test PLA, since these types of parts tend to be used in potentially hot car interiors.