VW Beetle Magnetic Moving Key Holder

This cute bug holds your keys with magnets and moves both bonnet & boot in unison when attached.

Updates

• v1.1 - I've lengthened the linkages slightly. This allows more travel on the mechanism and helps smaller keychains make contact with both magnets.
  • I've included GCODE for v1.1 linkages, or you can download the full 3mf.
  • Included a (hidden) mounting standoff block in the 3mf to help stick to a wall. Just glue to the Back.

Materials

You'll need:

• PLA filament
• 2 x 8x3mm Magnets (100 of these are <$12)
• [Optional] Super Glue

Printed Components

• All the parts fit on a Prusa Mini (180x180mm) bed and are included in the file.
• They're separated and named, so you can easily print in different colors / materials if you care to do so.
• 1 x Back - Contains all the mounting / pivot pins for the moving components.
• 1 x Front - Decorated front with the Beetle details.
• 1 x Bonnet & 1 x Boot - The externally moving pieces.
• 1 x Actuator - The moving piece which contacts with the keyring to move everything.
• 2 x Linkages - Connect the Actuator, to the Bonnet and Boot via pivot pins in the Back

Print Instructions

• 0.4mm nozzle @ 0.2mm layer or less.
  • My test prints are all 0.5mm nozzle @ 0.2mm layer.
• No supports are required.
• Min 3 top layers - Exactly 2 perimeters.
  • Any fewer top layers and the quality may suffer due to infill.
  • Any more perimeters and the surface detail may be lost.
• 15% infill.
• As the top face is the display side, it's useful to have your extrusion rate dialed in otherwise the face can get messy. I had some luck with ironing, but that also benefits from a dialed extrusion rate.
• PLA is recommended due to the bridging.
  • I tried PETG, it'd be fine for the Back, but the bridging on the Front may be a struggle.
• If your bridges look messy then try printing the Front at a lower temperature to improve bridging.
  • The bridges need to be clean as there isn't a lot of clearance when assembled.
  • I've included a picture of how my bridging turned out for reference.
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• Watch out for elephant foot on the Linkages and the Bonnet and Boot. If the base spreads too much due to filament / bed heat, then the holes may not fit over the pivot pins.
• The main Bonnet & Boot pivots are the weakest link, good layer adhesion is valuable here. I've only had issues with matte PolyTerra PLA. Others have been fine.

Assembly

• Lay all the pieces out on the Back piece.
  • Bonnet, Boot, and Actuator pieces sit flush on the Back.
  • 2 Linkages connect between the pivot pins.
• Insert the magnets into the Back piece.
  • Works best with opposing poles facing out. E.g. the magnets are slightly repelling each other.
  • They should hold in place without glue when the Front is snapped on, but depending on the print quality they may be a tad too lose, so glue can make sure they stay.
• Snap on the Front
  • Designed to be a press fit, I've found it varies depending on your flow rate.
  • Suggest gluing with super glue once you're happy to ensure it doesn't pop off the wall.
• Mount to the wall.
  • I've left this up to the reader. I'd suggest printing a rectangular standoff (e.g. just a Box shape in PrusaSlicer) and scale it based on how far from the wall you'd want.
  • You can then glue the standoff (box) to the Back, then attach to the wall with double-sided tape. 

This is a greatly improved version of my hanging key holder, which had independent hooks for 2 sets of keys.