Models visualize how an object (car, machine etc) looks from actual data used to construct the real thing. Your data can be obtained from blueprints, CAD files, photographs, and testimony from expert/lay/eye witnesses intimately familiar with the real thing.
Demonstrations show how a physical principle really works. You may need to explain the inner workings of a machine; however, you are not illustrating the expert's opinion in a case; it is just a tutorial showing background information jurors need to understand the expert's opinion. Demonstrations must conform to the relevant laws of physics, chemistry, biology etc.
Event Sequence Reconstructions a.k.a. Telling a Story show how events at issue happened. You may need both the expert witness and the artist/producer of the animation to lay proper foundation.
Simulations a.k.a. Actual Re-enactments have the forensic expert/engineer using specially written software to "re-create" an event or simulate reality inside a computer. The resulting animated re-enactment or diagram is a representation of calculations (speed and weight of the car, road conditions, financial forecasting) that have taken place inside the computer. Your expert must be able to say under Rule 703 that the software is the type used by experts in this field and Rule 901(b)(9).
Lay Your Foundations for Admitting Animations:
Qualify Your Expert Witness under Rule 901(b)(9); your expert must be able to support the reasonable use of their data in the animation; the animation artist must be prepared to testify that the system/software used to produce the animation produces fair and accurate results.
Qualify Your Computer Hardware & Software; you must be able to show the commercial, non-litigation, analytical applications of the software/hardware used to produce the animation.
Qualify Your Data; the data used to construct animated models, demonstrations, or reconstructions (e.g. expert witness calculations, models, or opinions; lay "eye" witness testimony; physical measurements, photographs, CAD or blueprint drawings or technical documents, data recorders) must be identified and verified. The source of this data must be identified; hard copy of this data could required in court.
Input Quality Check; a witness should be able to describe the details and methods employed to input (3) data into both the expert's and animator's computer; accuracy checks should be verified.
Your Expert Witnesses should be able to identify and defend their assumptions of what and how something happened.
Qualify Your Presentation/Display Media; your presentation media (e.g hard-drive, CD-ROM, videotape shown on a tv monitor, digital video projector etc) must show the computer-originated animation accurately (e.g. color, etc).