Prototypes are an essential part of the product development process. Prototypes test the design, durability and details of a product before it is mass produced. There are many options for prototype production and it can be difficult to narrow down. Below is a breakdown of popular prototyping methods that will make the process a little less stressful.

3D printing vs. CNC machining

3D printing is an additive method of production. A 3D-printing machine builds a product or part layer-by-layer until the final 3D object is created. 3D printers can create a product out of polylactic acid, acrylonitrile butadiene styrene, nylon, resins, thermoplastics and more.

Computer numerical control (CNC) machining is a subtractive method of production. CNC mills are computer controlled and have sharp, rotating tools that carve and cut a prototype from a block of solid material. The material could be metal alloys, softwoods, hardwoods, thermoplastics, acrylic, modeling foams or machine wax. Each material requires a different subtractive tool.

In comparison, a job that a CNC mill completes in an hour might take a 3D printer a whole day. CNC machining would be the right choice for a project that needs to be produced quickly. CNC mills are better at creating fine details, but they are messy and loud. CNC mills do not have an enclosed space, so any material being cut or carved away is not contained and clutters the nearby environment. A 3D printer builds projects layer-by-layer with no noise or mess. 3D printers can work with a wider variety of materials than a CNC mill. 3D printing is great for the biomedical, building and construction and aerospace industries, among others, while CNC machines are better for manufacturing and creating robust, precise and heat-resistant prototypes.

Vacuum casting vs. rapid tooling

Vacuum casting is a prototyping method in which liquids are vacuumed into a mold to create a prototype. This method provides a variety of options in hardness, materials and finish, making it perfect for creating small details. Operations can be repeated dozens of times to create identical products in a few hours. Vacuum casting is good for small-scale production and projects that require a low volume of prototypes to be produced quickly.

Rapid tooling quickly creates a mold, instead of a part or prototype, which is then used to create a prototype using aluminum or steel. This process builds a mold or plastic part within a matter of hours. Rapid tooling has a shorter tooling time and lower cost than traditional production methods. Because this method is so fast, prototypes lack the high quality and longevity of other prototyping methods. Rapid tooling can quickly create hundreds of prototypes, which is great, as long as they do not need to be perfect.

Choosing between these two processes comes down to how many products need to be made, and if small details are required. If a small number of design prototypes are needed quickly, then vacuum casting is the right choice. But if hundreds of prototypes that will go through testing are needed, then rapid tooling would be optimal.

Metal 3D printing vs. sheet metal prototyping

Figure 1. Metal 3D printing a part, layer-by-layer.Figure 1. Metal 3D printing a part, layer-by-layer.Metal 3D printing is 3D printing, but with metal. These 3D printers print a prototype layer-by-layer with metal and lasers selectively fusing deposited fine metal powder. Metal 3D printing can be used with aluminum, steel, brass, copper, bronze, sterling silver, gold, platinum and titanium. Metal 3D printing creates lightweight and detailed prototypes.

Sheet metal prototyping creates a prototype by bending, stretching and cutting metal until it forms the desired product. Metals that can be used with sheet metal prototyping are aluminum, copper, stainless steel, steel and zinc. Sheet metal prototyping creates durable parts, making it a good option for prototypes that will endure durability tests.

Metal 3D printing is typically used for projects that require any special tooling to create a prototype. For a limited time-run of a prototype, metal 3D printing is faster, cheaper and easier than sheet metal prototyping. But sheet metal prototyping is a better choice if a prototype needs to be produced in large quantities.


Each of these methods have different considerations. Yet there is a method that is right for each prototype and project. Visit the 3E Rapid Prototyping Limited site to learn more about these prototyping methods.