Doc's demonstration model of Courthouse Square as it existed in 1986.

" The candles masquerading as lamp posts were the nicest touch, Doc Brown thought, moving several steps backwards to admire his work. / "Very good," he murmured, smiling. "Maybe I'll keep it up until Christmas and use it as a garden." / He had spent most of the afternoon planning and constructing his own replica of Hill Valley's Town Square. Set up on a large piece of plywood, it consisted primarily of a piece of wood with a watch strapped around it (the clock tower of the courthouse) with a "lightning rod" (a nail) attached to the top. A wire ran from the lightning rod down across the square and between two lamp posts across the street. Near the lamp posts sat a windup toy car with a small wire sticking straight up from the back. To the wire was attached a hook. / Consulting his worksheet which contained lines of statistics and computations, Doc Brown nodded. He was sure it would work. "
—From Back to the Future by George Gipe (quote, page 183)

A demonstration model is a model that shows how a plan can be achieved through the use of physical objects.


Dr. Emmett Brown built two demonstration models to illustrate to Marty McFly how to get the DeLorean time machine to travel through time. However, Doc would always regret on each occasion about the crudity of the model as well as not having had time to either paint it or get it to scale; fortunately, Marty always reassured him that the model looked fine.

Doc's 1885 demonstration model[]

1885 Demonstration Model

Doc shows Marty his 1885 model of Hill Valley.

Minature DeLorean

The miniature DeLorean model, clearly labeled as TIME MACHINE, used on the 1885 demonstration model.

BTTF Minature Train

The model train was used on the 1885 demonstration model.

" Doc smiled tautly. "All right, Marty, let me show you the entire plan and layout." He waved for Marty to follow him over to the far side of the barn. There, on a weathered, rough-hewn table, was another of Doc's famous homemade table-top models, full of wooden blocks, toys, scrap metal and anything else Doc could scavenge from 1885. Marty realized the model was supposed to be the town and immediate surroundings of Hill Valley 1885. Marty glanced over at his friend. He noticed that Doc looked a little haggard. While Marty had slept, the inventor must have been busy on this table. "
—From Back to the Future Part III by Craig Shaw Gardner (quote, page 105)
Doc: "Marty, once more let's go over the entire plan and layout. I apologize for the crudity of this model, but I just..."
Marty: "Yeah, I know, Doc, it’s not to scale. It’s okay, Doc."
Doc: "Alright."
— Doc and Marty in 1885 about to devise the plan to return to 1985, Wav
"The shop appeared to be empty. Even the horses were gone. Perhaps it was Emmett she [Clara] had seen, riding away with young Clint. / She spotted a table-top model of some sort pushed up against one of the walls. It was partially covered by canvas, but once she pulled the covering off, she realized it was a tiny reproduction of Hill Valley, much like the map she had seen in the waiting room of the train depot, with Main Street, the courthouse tower, the Palace Saloon, even the train station. And running from the train station were a set of miniature tracks, with a point at the far end of the tracks marked STOP TRAIN HERE — a point that, if she understood this model reconstruction, was very near the ravine where Emmett had saved her! / Stop train here? Was this the mystery that Emmett wouldn't tell her about? Why would they want to stop a train? / Well, Clara decided, she was about to find out."
—From Back to the Future Part III by Craig Shaw Gardner (quote, page 180)

The 1885 model was built in Doc's livery stable on September 4 and September 5 of that year, mostly out of wood parts. It featured the main railroad line which spurred off into Carson Spur. Carson Spur terminated three miles down the track at Shonash Ravine. Other landmarks that Doc added included the silver mine where the DeLorean would be loaded onto the tracks and the locomotive would begin to push it. The Point of No Return was represented by a windmill, indicating it would be too late to stop the train before the edge of the ravine on the 1885 demonstration model.

Doc and Marty ran the experiment with the model train on one side. It was powered by a form of electric motor that Doc hooked up to the tracks, which passed current through them. They both watched as the train came around the bend, hooked onto the spur, and pushed the miniature DeLorean model to the edge. Doc caught the model DeLorean just as it drove off into the 'ravine'. Soon thereafter, Clara arrived at the door of the stable. 

On September 7, Clara returned to the livery stable upon learning (from passengers on the train) how heartbroken Doc was over their breakup the previous night. Clara found Doc's demonstration model, including the miniature DeLorean. As a result, she learned Doc was indeed telling her the truth, and proceeded to follow him as he and Marty were initiating their plan to return to 1985.

Doc's 1955 demonstration model[]

Demo model 1955

Doc shows Marty his model of downtown Hill Valley.

1955 Toy Cadillac

The original Cadillac toy car as used on-screen. Note the scorched interior where the car caught fire.

Doc: "Let me show you my plan for sending you home. Please excuse the crudity of this model. I didn't have time to build it to scale or to paint it."
Marty: "It's good."
Doc: "Oh, thank you. Thank you."
— Doc shows his model to Marty in 1955, Wav

The 1955 model was built by Doc's younger self in his garage on November 7 from paper, cardboard boxes, metal containers, bottles, and salt and pepper shakers all painted to a gray color. The model was surprisingly accurate in representing Courthouse Square.

Doc gave Marty a toy car that had to be wound up to travel down the road. Doc hooked up to a power source and pointed an alligator clip to the pole on the model of the Hill Valley Courthouse. He instructed Marty to release the car, and timed the 'lightning' with its intersection of the cable. The result was an explosion on the model table, with the car in flames. The burning model car drove off the table and rolled along the floor towards a large cloth, setting it on fire. Doc gasped in panic and ran to put out the fire with a fire extinguisher. Soon thereafter, Lorraine was at the door. The toy car used was a Cadillac from the 1950s.                

Days later, Marty examined the remains of the model after returning from 1985 as Doc read through his future self's letter.

In 1986, Marty found Doc's notebook in the model of the Courthouse.

Doc's Institute of Future Technology demonstration model[]


Doc shows the audience a new model.

The Institute of Future Technology model was again built by Doc to demonstrate to the time travel volunteers at the Institute exactly how time travel worked. Doc put a miniature DeLorean time machine onto a ping pong table with some makeshift buildings on it, sent the DeLorean down on a track to a flag that read RE-ENTRY, where it burst into flames. It finally stopped an unknown distance from the table, wildly spinning. Doc ran over with an extinguisher and put the fire out.

Behind the scenes[]

  • The 1885 train and DeLorean was sold for around US$30,000.00 on December 16, 2011 and can be found on icollector here.
  • The 1955 toy Cadillac can also be found on icollector here.
  • The 1955 demonstration model was built by art director Todd Hallowell and Michael Scheffe (the film's DeLorean Construction Coordinator). When Doc apologises to Marty for the model's crudeness, he states that he "didn't have time to build it to scale or paint it". In truth, Hallowell and Scheffe both spent weeks designing and constructing the model.
  • According to Todd Hallowell, the appearance of the 1955 demonstration model was inspired by the cover of the Supertramp album Breakfast in America.


External links[]