My parents recently decided to change out our old door lock for a new, keypad-controlled system. However, this new technology renders the practice of hiding a spare key impossible. Instead of making my guests memorize the code, I decided to laser cut the four digit password onto the bottom of a rock. The final product turned out great! This project can make for a wonderful conversation piece or gift.

Let's get started!

Step 1: Select the Rock

Some stones can be laser cut with more ease than others. Try to look for a rock with these qualities:

- Flat, smooth surfaces on both sides. While being engraved, the rock needs to be able to lay in a secure position. Also, the top face cannot have any vertical protrusions.

- A size to fit the job. Don't make your neighbors lift up a boulder every time they go to feed your cats!

- A uniform texture and appearance. The laser will react differently to different materials. With a chipped rock, some numbers may become illegible.

As you can see from the above pictures, I did not entirely follow my own guidelines. The best stone I could find was only flat on one side. Fortunately, it was very easy to put some painters tape on the pyramidal section and secure it to the cutting bed flat face up. If you have access to a beach, I would recommend searching there.

Step 2: Prepare the Software

First, open the laser cutting software of your choice! Ziven and I used Corel Draw. Type out your keycode (or whatever you want engraved on the rock) into the program. For text, I recommend using a font that is thick and legible -- I used Brittanica Bold. Now let's cut it out!

Step 3: Laser Cut the Rock!

If your rock is flat on both sides, just lay it down on the cutting bed! Unfortunately, mine wasn't so I had to adhere it with some blue painters tape. Next, you'll need to calibrate the nozzle height -- this process will be different for everyone so I won't cover it in depth. Finally, plug in some numbers for speed and intensity and run it! The first time we started the job, the rock was not getting marked at all due to a low power setting. Experiment a little until you are satisfied with the product. Mine turned out awesome!

Step 4: Finish the Project!

Remove the stone, and run some cold water over it to remove any excess powder. Hopefully your rock looks awesome! If there is a code on it, hide it near your front door! Or give it away as a present! Lastly, I think that laser cut rocks would make an great item to sell. You could inscribe sayings like "You (rock) my world!"

I hope this Instructable was enjoyable to read. If you have any questions or concerns, please let me know in the comment section below!