Introduction: Ball Lock Puzzle (3D Print)

About: I like to design and build random things.

This is my variant of the classic Bamboo Puzzle. The goal is to open the box to retrieve your treasure. I liked the look of the original puzzle but the solution was way too simple. Unfortunately, I found out that you could actually solve it by just shaking it back and forth. :(

Besides the puzzle being printable (STL files attached at the end), I've added additional steps and locking features to add to the complexity of the puzzle. I've also sized the overall box to hold a ball (golf, ping-pong, mini-tennis) or any other object of equivalent size.

Step 1: How It Works

I tried to capture the solution in the text but it's actually easier to see in the videos below.

This video shows an animation of the puzzle.

This video shows the actual puzzle.

Step 2: Box

The box is 2.75" x 2.75" x 3" tall. The flange on the top brings the overall dimensions to 3" square by 3.125" tall. All walls are 3/16" thick. Holes were oversized to account for potential misalignment in the print.

Step 3: Pins

There are two pins: Large and Small. The Large Pin has two holes and slots and an indentation on one side. The Small Pin goes through the Large Pin. The narrow sections move within the slots on the Large Pins. You will need to print two of each.

Step 4: Lid

The Lid covers the top of the box. The slots on the bottom side are sized for the Small Pins. These pins prevent the top from being removed. The two protrusions on the bottom-center side are locking features for the Large Pins.

Step 5: Lid Assembly

The Lid has a turnable Knob on the top. On the bottom side is a plate that pulls against the Large Pins. This locks the Large Pins in the centered position. You will need a #6 Wood Screw for the attachment.

Step 6: Solution Steps

From the Locked Position:

  1. Turn Knob 90 degrees
  2. Raise Lid up as far as it will go (~ 1/8")
  3. Push one Large Pin to one side
  4. Push second Large Pin to the other side (note that this could be reversed)
  5. Remove 1st Small Pin
  6. Remove 2nd Small Pin
  7. Remove Lid
  8. Remove 1st Large Pin
  9. Remove 2nd Large Pin
  10. Remove Ball!

Step 7: Drawing

I've attached a dimensioned drawing for the woodworkers or anyone that would like to model their own.

Step 8: STL Files

All files were printed without supporting material. PLA and 50% infill was used for each. A #6 screw (not shown) was also required.

Anything Goes Contest

Participated in the
Anything Goes Contest