I live in San Francisco where Sutro Tower is an integral part of the skyline. I can't help but think that, when viewed from certain angles, it looks like a giant fork!

The architectural landmarks in a city become our friends in a weird way. They're these ever-present figures that are always around wherever we look. We develop special attachments to them and their personalities. I was interested in exploring this intimacy by playing with their scale and form, and making them into tangible, playful, and functional objects that could accompany you into your house, and specifically your meals - the one place where you don't normally see these structures.

So i set out to see just what it would look like to prototype a Sutro Tower Fork!

In fact I got carried away and even made a Transamerica Pyramid Knife, and designed a Coit Tower Spoon!

I'll share how I went about the prototyping process, and what I would do going forward to turn them into finished products.

## Step 1: Prepare a Vector Image of Sutro Tower

The goal was to find a silhouette from the right angle to give that fork shape.

I found a great image from Michael Huang's www.citycardspotter.com project.

Opening it up in Adobe Illustrator (CS5), the next step was to trace it. The clear black and white contrast made for very easy tracing. Otherwise some photoshop prep wouldve been required. I did the tracing by selecting the object, going to Object>Live Trace>Live Tracing Options. IMPORTANT: I selected the "Ignore White" checkbox. Otherwise it wouldve traced the white spaces between the tower giving me the inverse of what I want. Once checked, click Ok.

After tracing I saved as an .SVG to prep it for import into 3D modeling.

## Step 2: Turn Vector Into 3D Model of Fork

For 3D modeling i used Autodesk 123D Design. Oddly, you can only import .SVG files using their online browser based version.

I imported into their browser version, saved it to my account on their cloud, and then used my desktop version to re-open the file and do the heavy lifting.

Now i needed to turn this slightly extruded silhouette into a more curved ergonomic form based on a fork.

First, I switched my units to inches and got the whole object up to scale at about 6.5 inches long.

Next, I separated the handle from the head at the point where the structure tapers together.

Then, I moved the handle back and up about .5 inches. I rotated it clockwise 8 degrees. (I never measured a fork but was eyeballing these measurements.)

Next, I thinned both the handle and the head to different thicknesses by selecting each face and using the PUSH/PULL command to essentially reverse extrude.

Finally, I reconnected the two pieces by drawing a sketch onto the facing sides and using the LOFT command.

and voila! the tower was now forkified!

## Step 3: Create 3D Model for Knife

This is almost comically simple.

I used Sketchup's Warehouse to find existing 3D models of the Transamerica Pyramid and of a knife. Once imported it was as simple as lining them up and overlapping them with each other.

I used Sketchup's STL plugin to export the file as an .STL to be readable by the Makerbot.

## Step 4: 3D Print

I used my friend's Makerbot Replicator for 3D Printing. I would've loved a higher quality printer but it was all i had for rapid prototyping ;)

I imported the .STL files one at a time into makerbot, checked everything was okay, checked my settings(infill, temperature, speed, etc) and hit print! You can see my settings in the screenshots. You're own machine's optimal settings may vary. Printing each took about 1.5 hours.

The knife was able to print upright. For the fork, it automatically created lofting underneath the angled handle to support it while printing.

After printing i used a knife to cut away this lofting and the base layer. This was harder than i would've liked and could ideally be avoided on a better printer. Unfortunately the head of the fork was too delicate to fully cut it away from the base layer without totally destroying it, so I left it alone. Thats why the fork looks more like a spatula...

## Step 5: Looking Forward...

To clarify, this was an experiment in rapidly prototyping an idea, not in producing a final product.

And it was surprisingly great! With some future modifications i'd definitely love to explore bringing them into reality as fully functional, beautiful silverware.

Future Modifications

• Painting the fork red and white to match the actual tower
• Making the shaft of the fork less on a plane and more like the 3D tripod of the actual tower
• Enlarging the size of the knife on the transamerica pyramid.
• Using a high quality 3D metal printer
• Exploring options for casting molds and producing at scale
• Coit Tower Spoon anyone!?

Thanks for reading along! Hopefully this inspires you to go out and re-imagine the world and the objects around you in your own unique way!

my god..this is amazing...!! :) I've already started imagining things in a totally different way..such a cool instructable..thanks for sharing..!