You can identify a model built by Heather Oppitz by the “little bit of DNA” she leaves behind on each one.

Oppitz doesn't build model planes or trains. Instead, she puts together tiny houses and buildings from scratch. It has been her profession for six years, and she literally bleeds for work. In an era in which architects inexpensively can generate realistic three-dimensional computer models at lightning speed, model building would seem to be a quaint relic.

However, the computer images can't replace a physical model, said Kyle St. Peter, senior vice president and marketing principal for St. Louis-based Hellmuth, Obata & Kassabaum Inc.

Oppitz builds her models for architectural firm Cannon Design, also of St. Louis. Her craft requires a careful attention to detail and minute precision as well as use of power tools, often all at the same time.

Accidents — mostly minor, sometimes not — are common.

Despite the professional hazards, Oppitz treasures the creativity that comes with her job. “It is the kind of job where I enjoy getting up and going to work each day,” she said.

Creating a model is like constructing an actual building, Oppitz said, only in miniature. “The difference is with a model, you can tear it up and start over,” she said.

And instead of brick and concrete, models are made from Plexiglas, polycarbonate sheets and gator board — a dense and durable composite of polystyrene. Oppitz often starts with the 3-D graphics generated by the design and architecture team. They provide more clarity on the dimensions of a structure than hand-drawn two-dimensional plans. But what looks perfect in a computer model may not be feasible in the real world.

“With a model, you can see it (the building), touch it, play with it,” said George Nikolajevich, design principal for Cannon. “You can see where the mistakes are.”

Depending on the complexity of the project and the detail required in the model, Oppitz said, it can take days, weeks or even months to build a model.

Study models — the most simple ones — are put together for the architecture and design teams to get a feel for the overall look of the design and develop it further. Oppitz also builds models that focus on the interior spaces, models that show the location of different buildings and other landscaping elements, and exploratory models meant to test the viability of a design.

Presentation models require the most complex — and time-consuming — work. These typically are showcased in a developer's sales office or in the board room of a company.

Presentation models are supposed to offer a realistic view of a development, so attention to small details is critical. Such models will include trees, cars in a parking lot and figurines for people. While many of the props can be bought out of a catalog, some have to be hand-crafted.

When it comes to presentation model building, success clearly is in the details. Oppitz recalls one recent model for a large development in the Middle East, where the project manager asked her to use only male figurines.

“It's because the only female figurines you can buy all wear skirts,” she said. “Seeing women in skirts would be very offensive to people in the Middle East.”

Deadlines are a huge challenge for model builders.

The architects “usually come to you at the last minute and want a model,” Oppitz said. “And I always protest because they have been working with it for weeks or months and they want me to translate it into a model in hours or days.”

That means a lot of late nights and caffeine-powered days working on models, sometimes leading to accidents.

“After two straight days of barely sleeping and working on the same model, your eyes glaze over,” Oppitz said.

Such a situation led to her worst injury.

“It was 2 a.m., I was sleep deprived and trying to cut to one-thirtieth of an inch,” she said. “I got myself on the table saw.”

She sustained a nasty cut, a relatively benign outcome.

“I know a lot of model builders with missing digits,” she said. “I just hid my finger behind my back, held it tight to stop the blood and prayed really hard that I had lost a nail, not the top of my finger.”

Cuts are such a routine hazard that Oppitz has a quick fix: Super Glue. Model builders often use it for first aid, she said.

While many firms outsource their model building, those that employ them cite cost as a key factor. Outsourcing costs can add up quickly, said HOK's St. Peter.

“You could spend from $5,000 to $50,000 on a finished model,” St. Peter said. Outsourcing only the presentation models can cost more than $250,000 a year, he said. If the company outsourced all of its model building, it could add up to more than $500,000 a year. By comparison, the $300,000 HOK spends each year on its in-house model shop is a bargain.

“We work on about 50 projects a year on average,” St. Peter said. “That means there are literally hundreds of study models that get built in-house.”

Having an in-house model shop helps integrate the design process, said David Polzin, vice president and senior project designer for Cannon.

“We can have an ongoing dialogue with Heather, especially in the early design stages when the idea may not be completely formed,” Polzin said.

“There may be issues that emerge out of the model-building process that we may not have even thought of that could help us in the architecture design process.”

In-house model shops are not feasible for small operations, or if the firm needs models infrequently, said Bridget Bogan, senior associate and head of the design services studio for Lawrence Group Architects, based in St. Louis. The architecture team uses only presentation models and it is cheaper to outsource the work, Bogan said.

“Not all companies have the space for a model shop,” she said. “There may also be liability concerns with having certain big tools on site. It depends on each individual firm's preference.”

A well-equipped model shop would have a range of power tools and precision tools: table saws, planers, joiners and laser cutters. Along with cost and liability, Bogan said, detail also is important. Outside model shops are able to quickly create complex models, Bogan said.

Thomas Bergmann, principal in charge of Midwest operations for Cannon, doesn't agree.

“While we have great respect for these (outside model) firms, we believe we can produce the same or better quality (models) and more efficiently with an internal resource,” Bergmann said.

Indeed, Cannon is ramping up its model building department. Cannon hired Oppitz six months ago as model-shop manager, after she worked for HOK for more than five years. Cannon is investing $60,000 in its new model studio, in addition to the tools the company already owned.

The company also plans to hire additional model-shop staff. Bergmann thinks the money invested in the equipment — and on salaries — is well spent.

“Heather will be doing models eventually for the entire (North American division) of the company,” he said.

“The dialogue between the model maker and the design team is critical. You can't get that quick and immediate response by using a shop that does not know you, your design perspectives and desires.”