Mold designers can create their tool models using 3D solid modeling or surface-modeling software, or they can use programs that provide both types of functionality within one program.

Solid modeling typically involves part features that have a thickness, while surface tools make shell-type geometries. Exterior mold surfaces like the core, cavity, or parting line, and interior components such as a runner system can be designed with either system, though they may handle the tasks in different ways and be easier or more difficult to use.

Data developed in a solids or surface environment can be managed two ways. A parametric model keeps a history of the chronology of the mold design and also has intelligence allowing for relationships to be formed (“associativity”) between different patterns or features. For example, if a designer selects a mold base of a certain size, it is associated with a certain number of drilled holes, created with certain spacing on the plate, and having a certain diameter and depth. The advantage of a parametric modeler is its automatic updating of groups of related objects when an item associated to it changes. It also allows the designer to save and reuse all of the settings again in another tool plan, saving time.

A disadvantage of parametric software is that the designer cannot make even a small change to a feature without impacting all related groups of objects. So expanding one hole in the mold base may cause all the holes in the base to change–even if that is not what was intended.

So-called “history-free” modelers (also called explicit, dynamic, or direct modelers) do not associate one pattern or feature with another, do not create a history tree, and do not link associated components, allowing individual features to be changed independently. Users can thus create unusual geometries for components or patterns without affecting other standard components. Users can update the mold design quickly when just a few features are adjusted.