On November 15, 2013, the city of San Francisco was converted to Gotham City to fulfill the wish of 5-year old Miles Scott, a Leukemia survivor, who wanted to be Batman. For more information on Miles and his special day, check out:
http://sf.wish.org/wishes/wish-stories/i-wish-to-be/wish-to-be-batkid

I was honored to be a small part of Miles' day by creating the Key to the City of San Francisco, and the City of Gotham, which the Mayor presented to Miles at the end of the day. This Instructable documents my process for making the key, but the techniques I used can be used to create an incredible range of projects. I had a little over 12 hours to complete the project (three of which were used for sleeping). I also wouldn't have finished without the help of my buddy Arthur.

Step 1: The Artwork

The design of the key was based on an image I received from the Mayor's office of a previous key design. This gave me the main outline of the key, as well as a place to start for the artwork.

I used Inventor to make the outline that we would then use to cut out the key, by bringing in this reference image and tracing over it. This could have been done in something like Adobe Illustrator, but I'm used to using Inventor so that was just easier for me with my tight deadline.

After that was done, I moved into Adobe Illustrator for the remaining artwork. There were two sides to the key; the first was for San Francisco, and the second was for Gotham. I incorporated as much artwork from the reference as I could for the San Francisco side, and worked within the time I had to do the rest.

Step 2: Cutting the Key

We cut the key out of a 1/4" plate of aluminum using a water jet machine. A water jet works by shooting high pressure water mixed with sand through the sheet of aluminum. The machine is computer controlled, so we just had to import the 2D outline that I had drawn and the machine did most of the rest.

Step 3: Laser Etching the Artwork

Before we could etch the artwork onto the blank key, we had to prep the surface. We first sandblasted the entire thing to get a nice and even matte finish. Then we sprayed a coat of TherMark Laser marking ink . This was necessary for the laser to actually be able to etch onto the aluminum.

Once that was done, we used an Epilog 120W laser to cut a template out of wood so we knew where to place the key for engraving. Then we engraved both sides of the key.

Step 4: The Finished Key

Once both sides we engraved, we washed off the remaining TherMark spray, and handed it over to the Mayor's office. The key was then presented to BatKid.