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Locking Egg with Key - Great for Easter Egg Hunts and Geocaching!

Creation quality: 4.8/5 (3 votes)
Evaluation of members on the printability, utility, level of detail, etc.

  • 1 collection
  • 1 comment

Licence CC BY-SA
Last update 2022-04-07 at 00:34
Publication date 2022-04-03 at 18:44
Design number 682808
3D design format
SKP and STL Folder details Close
  • 1of7_LockingEggTopHalf.skp
  • 1of7_LockingEggTopHalf.stl
  • 2of7_LockingEggBottomHalf.skp
  • 2of7_LockingEggBottomHalf.stl
  • 3of7_LockingEggPin.skp
  • 3of7_LockingEggPin.stl
  • 4of7_LockingEggLid.skp
  • 4of7_LockingEggLid.stl
  • 5of7_LockingEggClip.skp
  • 5of7_LockingEggClip.stl
  • 6Aof7_LockingEggKeySquare.skp
  • 6Aof7_LockingEggKeySquare.stl
  • 6Bof7_LockingEggKeyTriangle.skp
  • 6Bof7_LockingEggKeyTriangle.stl
  • 6Cof7_LockingEggKeyPentagon.skp
  • 6Cof7_LockingEggKeyPentagon.stl
  • 7Aof7_LockingEggLockSquare.skp
  • 7Aof7_LockingEggLockSquare.stl
  • 7Bof7_LockingEggLockTriangle.skp
  • 7Bof7_LockingEggLockTriangle.stl
  • 7Cof7_LockingEggLockPentagon.skp
  • 7Cof7_LockingEggLockPentagon.stl
  • CalibrationThreads.stl
  • CalibrationThreads_PrintFirstToTestFit.skp

Learn more about the formats

3D printer file info

3D model description

Watch this video for a demonstration and assembly instructions:

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This locking Egg will be the highlight of your next Easter Egg hunt. There are three different lock shapes with three corresponding keys. Place keys and candy in the various eggs, lock them up, and hide them. Then give the hunters only one key. The idea is that the hunters will have to find an egg that matches their key in order to get the keys for the other eggs.

This is also a fun way to hide a geocache, though you may want to place the egg in a plastic bag to avoid the elements.

The locking mechanism uses a hidden barrel cam to move a pin up and down. I tried 10 or so various locking methods before I settled on the barrel cam.


  1. Slice and print the top and bottom of the egg, titled 1of7_LockingEggTopHalf and 2of7_LockingEggBottomHalf.

    Print as oriented. Supports are not required. I recommend a layer height of 0.2mm or smaller, wall thickness of 1.2mm, a bottom thickness of 0.6mm, and a top thickness of 0.8mm. Infill density of 12 percent or higher. I tried to allow for horizontal expansion in the design, so first try printing it without adjusting horizontal expansion, slicing tolerance, or x/y compensation. If it prints too tight or too loose, then you can use one of those slicing features to compensate. Threads are notorious for being the hardest item to print, so please be patient. If you want to save time while testing, you can print the included calibration test instead of the full model, but that is optional.

    Once the egg halves are printed, screw the threads in and out repeatedly to remove any stray particles. It may feel too tight on the first threading but should screw easily after ten seconds of doing this.

  2. Slice and print 3of7_LockingEggPin, 4of7_LockingEggLid, and 5of7_LockingEggClip using the same settings as above.

  3. Now you need to decide which key shape you want. There are three options: Square, Triangle, and Pentagon. If you only print one style, I recommend the Square Key.

    Print 6of7_LockingEggKey... and 7of7_LockingEggLock... in the shape you choose, using the same settings as above. The lock file is a barrel cam that moves the pin up and down. I had no trouble printing the lock without supports, but if you run into trouble, you can add supports to that file only.

  4. Make sure the Pin end can slide freely in the Lock (barrel cam) groove. The pin should pass over the bump on each end of the groove without much resistance. If it doesn't, sand the groove until you get an easy slide. Refer to the video to see what I mean.

  5. Follow this assembly video to see how to put together. You'll need some small needle nose pliers.

I am also including the original Sketchup files. Feel free to remix this with surface skins and whatever you can dream up!

This thing is a remix from my own simple threaded Easter Egg, also available on Cults. Click on my profile to see my other models.

Happy Easter!


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