Prototypes and Models: It's All in the Details
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Prototypes and Models: It’s All in the Details

General Plastics boasts of a talented team of chemists and engineers, and a technical sales group who are constantly pushing the envelope to stay ahead of the competition. From this mindset, General Plastics has created products that have satisfied a wide range of applications. As Mitch Johnson, Vice President of Materials Technology, explains, “competition always drives improvement. We always strive to stay ahead and provide value and quality for our customers. This means offering creative solutions for diverse industries.”

Among the markets that General Plastics has found success in is the prototype and modeling market.

General Plastics’ LAST-A-FOAM® provides dimensionally stable and precise materials. Whether you’re building a particular product prototype, design model or a topographical map, the properties of our foams lend themselves to these types of applications. Specifically, Johnson recommends the FR-7100 and FR-4600 to accommodate the needs of most prototyping and modeling applications.


Product prototypes and design modelsLow cost and easy to use, the LAST-A-FOAM® FR-7100 is an ideal choice when it comes to selecting foam for applications requiring excellent mechanical properties (less deformation) and uniform cells. With a glass transition temperature of 245 degrees Fahrenheit, it can also handle many of the manufacturing processes to create finished prototypes and models.

The unique formulation of this cellular plastic board stock enables excellent adhesion to many adhesives, primers and paints, so it can be easily finished with excellent results. The resultant physical properties of the foam allow users the ability to machine with standard high-speed steel cutting tools, water jets, or even traditional wood-carving tools.

The FR-7100 foam is available in large-size billets and densities ranging from 4 to 40 pounds per cubic foot. Since the price will increase with density, customers can fine-tune what their process requires to save on cost by selecting the density that is right for them.


  • Uniform structure supports very even finishes
  • Closed-cell foam does not absorb water or moisture
  • Easily painted and bonded
  • Economical and versatile
  • Dimensionally stable
  • Grain-free surface
  • Easily shaped with a variety of cutting processes


LAST-A-FOAM® FR-4500 was the premium product for models and prototypes for more than a decade. General Plastics saw a need for foam that has similar physical properties as FR-4500, but with finer cell structure. This resulted to the creation of FR-4600 microcellular polyurethane foam.

Microcell polyurthane foamWith the smoothest finish of all LAST-A-FOAM® products, this foam excels in applications where intricate details and finish quality are of vital importance. Advanced microcell technology creates the grain-free, ultra-smooth surface so less sanding, priming, and finishing are involved. This significantly reduces process time and cost. Since multiple layers of coating would not be necessary to achieve the desired finish, users can retain very fine details. What’s more, its finer cell structure is comparable to higher-density products without the added cost and weight.

This foam can be easily shaped using CAD/CAM routers and CNC machines, or woodworking tools. The FR-4600’s exceptional machining characteristics also make it an efficient material to create intricately patterned prototypes and models.

A tougher material than the FR-7100, the FR-4600 is a good product to use for exterior architectural features where it may be subjected to impact. Architectural models, topographical maps, decorative moldings, and 3D signage – applications where surface finish and detail are the number one priority, make the FR-4600 foam series the ideal material.


  • Ultra smooth finish
  • Lighter, less abrasive than syntactic boards
  • Creates intricate, 3-D details
  • Faster sealing and finishing
  • Dimensionally stable
  • Special formulation creates shavings, so it is less dusty when machined
  • Easily finished with most resin or coating system
  • Reduced cutting tool abrasion
  • Large sheets up to 60″ x 120″
  • Easily bonded for large block sizes

General Plastics is privileged to support engineers and design teams across dynamic industries. Contact us today at 866-825-1378 to get the best material for your prototype or modeling application.


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