Introduction: Emergency Coin Safe - Puzzle - 3D Printed

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About: I love to craft and my sons and grandchildren keep me going!

It's a pretty silly idea to keep a few coins or a banknote as a nest egg in a box like this, especially as you then have to know how to open it.

This small safe box, consisting of three printed elements, has it all. The bottom element contains a cavity in which small objects such as rings, coins or a folded note can be stored. An ideal little gift for family and friends ... with a lucky penny inside, for example!

The idea for this object came to me through the publication of the Nickel Puzzle Box by scorch on Thingiverse https://www.thingiverse.com/thing:1584817. He in turn got the idea for his realisation from Craftmanspace https://www.craftsmanspace.com/free-projects/ball-puzzle-box-plan.html#google_vignette. About twice the size of my model and made of wood. My design is a combination of both - 3D printed.

If you don't know the trick, opening this small safe requires a lot of patience! Many give up. Sometimes the solution is found by chance ... which does not mean that the solution has been found!

It is relatively quick to make … if the necessary parts are available 😉

Dimensions: L60xW30xH30

Supplies

You need:

  1. 3D printer
  2. filament (different colors)
  3. Phillips screw Ø 4 x 30 mm
  4. self-locking nut Ø 4 mm
  5. steel ball Ø 7 mm
  6. Phillips screwdriver

Attachments

Step 1: Printing

Print settings:

  1. printer brand: Prusa
  2. printer: MK3S, Mini
  3. supports: no
  4. resolution: 0,2
  5. infill: 15%
  6. filament brand: Prusa; ICE
  7. filament color: Galaxy Black; Romantic Red, Wintershine White
  8. filament material: PLA

Remark: As all parts are designed to fit very precisely, it may happen that you have to rework one or the other part a bit with sandpaper and/or cutter due to different dimensional accuracy of the printers and the different behavior of the filaments.

Step 2: Assembly

For the assembly you need:

  1. the printed parts
  2. Phillips screw Ø 4 x 30 mm
  3. self-locking nut Ø 4 mm
  4. steel ball Ø 7 mm
  5. Phillips screwdriver

If possible, a self-locking nut should be used, as a normal nut would quickly come loose due to the rotational movements.

With the help of the pictures you can place the 3 parts on top of each other. But don't forget to place the ball in the recess in the middle section.

Step 3: How to Open the Safe

As you have assembled this object yourself, the solution will surely be clear to you. For all those who just want to have a look at this publication, here are the individual steps:

  1. hold the box as shown in the first picture. The screw head points upwards.
  2. now you must turn the box upside down. Now the nut points upwards (2nd picture). The ball falls from middle part into the slot on the top part.
  3. now turn the lower part towards you (3rd picture).
  4. turn the box back again. The screw head points upwards again (4th) picture.
  5. now the middle part can be pushed to the right (5th picture).
  6. the locking nozzle is free and the middle part can be turned to the side (6th picture).

To reactivate the box, go back the way you came.

Step 4: Colour Suggestions