Narrator: This machine is carving out
a life-size Ford Mustang from hundreds of pounds of clay.
It's arguably the most important step in designing a car,
even though most car owners know nothing about the process.
Car companies have used clay models for almost 100 years
on nearly every car you see on the road,
from this Mustang to this $28 million Rolls Royce.
Mark: I mean, I come across people
every single day that do not understand the concept
of why we would make a full-size car out of clay
and then finish it in a way
where it looks exactly the same as the production vehicle.
Narrator: But today, companies
are straying away from clay.
Modeling is an expensive process that goes up in price
based on the company and the complexity of the vehicle.
Exotic hypercar brands like Bugatti
have dropped upwards of $650,000.
Automakers now have high-tech virtual reality software
that lets them design and examine every inch of their cars.
So why do some companies still use
up to 100 tons of clay each year?
And why do some models take years to build?
Clay models are built
in top-secret studios that are
even more restricted than manufacturing plants.
Inside, designers develop vehicles that
haven't even been announced yet.
This is the car industry's Area 51.
Mark: Yeah, I mean, we work
in a secure facility that only a few members
of the site can actually get into.
So it's special permissions to get into here.
Narrator: Mark Sadler's been a clay modeler for decades
and now manages teams for Bentley.
He worked on signature models like the Bentayga SUV.
The clay comes in bars or cylinders
the size of tennis ball cans.
It's closer to the Play-Doh we played with as kids.
Traditional water-based ceramic clay
would dry out and harden too fast.
This specialty clay is more sticky and malleable.
Modeling teams first turn design sketches
into multiple scaled-down clay models
about just over a meter long.
Once they decide on the design
they want to move forward with,
3D scanners convert it into digital graphics.
Those can be edited further with software
that can include VR aspects.
That data is then transferred to a milling machine.
The modeling team first builds a frame
out of steel and wood to support foam blocks.
Making a whole model out of solid clay
would be too expensive and weigh at least several tons.
To make the clay more workable,
they heat it for 24 hours
in a special oven set to around 140 degrees Fahrenheit.
Modelers spend a couple of days
slathering 1 to 4 inches of warm, soft clay
on different parts of the model.
Once it cools to room temperature and stiffens,
it's ready for shaping.
In just one to two days, the milling machine
can carve out a full-size model.
But it's not close to being finished yet.
Modelers still have to smooth out
surfaces, corners, and edges.
This is where craftsmanship becomes critical.
Mark: I've met people that have come
from the porcelain industry that have migrated
very quickly, very easily into the clay-modeling side.
But I've also met people that,
no matter how much training you give them,
how much guidance, they just don't get it.
Narrator: They also carve out important details
like hoods, rooflines, and fenders
all by hand.
Mark: I mean, you can have at least probably 60,
70 tools in your box that do similar things,
but do it in a slightly different way.
Narrator: Their tools may look
like medieval surgical instruments.
Very, very, very simple things.
I mean, this is quite a crude tool,
but it's almost like a cheese grater.
So you can actually scrape a lot of clay off
but keep the surface quite flat and level.
Narrator: But this strange collection of razor blades
and wires has been responsible
for some of history's most beautiful cars.
Clay modeling dates back to the 1930s,
but the technology has changed drastically.
Now, computer-driven machines take hours to do
what used to take days, or even weeks, of manual labor.
Still, the tools used for actual sculpting
are mostly the same.
This is a a very simple tool that we use,
and it's just, you just scrape it, like that.
There's these what we call slicks.
Now what these are a very thin steel,
but what it allows you to do is to shape,
and then you can use that shape
to drag down the surface of the clay.
Narrator: The real advantage of clay is versatility.
Modelers can experiment and make a change that may
or may not work but can be easily fixed.
If modelers make a mistake, they use a hot-air gun
to soften the area and either add more material
or remove it.
To give the most complete picture
of what the vehicle will look like,
3D printers produce headlights, grilles, mirrors, and more.
Mark: The hard parts, or the three-dimensional
printed parts, they develop with the model.
So they'll get more and more detailed
as they go along, and the materials
in those parts will, as well, will develop.
So what might be a painted part to begin with
will end up being a crystal part at the end.
Narrator: The team uses 3D scanners
to create a digital version of the model.
That way, it can be shared instantly
with a company's engineers and designers
all over the world.
Near the end of the process,
clay models are covered in a glossy film called Di-Noc
that resembles painted sheet metal.
It gives modelers an idea
of what the actual car will look like.
The film can help identify mistakes
in the bodywork that need to be corrected.
And modelers are no strangers to corrections.
Despite how much faster scanners and milling machines
have made this process, it can still take years
to finish a clay model.
Over a dozen changes can be made to the model
before it's given the green light.
Car designers may continue to adjust details
in the bodywork by just millimeters.
Engineers will make changes to its structure
that improve the vehicle's crash-test ratings.
When sculpting these different changes,
modelers rely on one tool everyone is familiar with: tape.
Mark: The tape that we use, it's a Scotch tape,
black tape, so that sticks onto the clay so that
when the designers want to change something,
or we want a more defined guide
to help us clean up surfaces,
we can put this on, and then we can work the surface to it.
Narrator: While these simple tweaks can be done by hand,
major changes require the model
to be completely re-milled from updated data.
The combination of materials and the amount of labor
is what leads to those six-figure price tags for automakers.
Bentley tries sticking to a strict 12-month time frame,
but it's not the case for everyone.
Designers spent over four years making
this Ford F-150 Raptor model
out of nearly 2,000 pounds of clay.
No matter the company, once the modeling team starts going,
they're racing against the clock.
Mark: The biggest challenge we always have is time.
And especially if I've got the head of the department
coming out, the head designer coming out,
and say, no, I'm not happy with that.
I need to change this, that, the wing, the whole body side.
It's trying to balance everybody's wishes and requests
and what they actually want to see, you know,
and to hit that deadline that we've got to hit.
Narrator: So what makes these expensive clay models
more useful than virtual ones?
For one, automakers can test a car's aerodynamics.
Computer programs help, but they need a real-life model
to thoroughly test this.
To do it, they use a giant wind tunnel.
As a massive fan spins, engineers use a smoke wand
to see how easily air will flow over, under,
and around the car on the road.
It's called drag, and it helps measure
how much energy a vehicle needs to move.
This informs how much fuel the car will eventually consume.
In some extreme cases, companies can spend
over 1,000 hours in the tunnel
testing a model's design
before committing to full-scale production.
And modelers are standing by,
ready to make adjustments on the spot.
But most importantly, models are used
to see how a car prototype actually looks.
They can see things like how natural light
plays on its curves.
Only a real 3D model can show how it will look
when it's actually on the road.
You're trying to create something
that will grab somebody's attention, and it will almost
get the heartstrings going, get the emotions going.
And sometimes, you just can't quite get it there
with digital or VR. You just can't do it.
So it needs that hands-on process.
Narrator: No matter how much more accurate
and reliable VR design technology becomes,
clay modelers like Mark don't see their practice
disappearing anytime soon.
You're always going to need a physical model
to verify the data that you receive.
I can see the generations coming through now
that are more used to using different software,
virtual reality, and there will be more confidence
in what they see virtually.
It does help the process.
It definitely helps speed up
the development of these products.
But I think there will ultimately always be a need
for a clay model of some form.