Are you tired of people stealing your pens. You need to write something down, but you can't find your pen anywhere. Here is one solution. This pen has a combination lock on it, so others cannot use your pen without the right code. 

Materials needed:

PLA

Ink tube from a basic clicking pen

knife or tool to clean up the pieces before assembly

Super glue

To assemble the pen:

1. trim about 1cm off the empty end of the ink tube.
2. print the inside first. Pause the printer at layer 31 with 0.12mm layers, and insert the ink tube with one tab pointing downwards into the slot and the other tab facing upward.
3. Print the rest of the pieces necessary. (You only need to print 3 out of 10 of the plates with the numbers you want for your combination.)
4. Clean all of the supports off the pieces and make sure the inside piece is nice a round so it fits inside the outer piece.
5. Insert the inside piece into the outside piece and make sure everything more smoothly.
6. Carefully glue the end piece onto the outer piece by turning the inside piece halfway between open and closed position and placing the top on.
7. Carefully glue the locks together by applying glue to the outer face of the tabs on the piece and placing it on the pen. Then place the other piece of the lock on the pen. Rotating the lock around the pen while glue dries will ensure the lock does not get glued in place.

8. Repeat step 7 two more times with your other lock pieces.

    

   The more you turn the locks the more they will loosen up and turn more easily.

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