Adventures in Thermoforming: Full Metal Molds and Inversion Casting
It’s been a long time since I’ve been this excited about a product because I can verifiably say that I eat and drink this stuff 24/7. Every now and then though, we turn something out that reminds me of why we went into this business. It’s not because these pieces belonged to the coolest characters in the galaxy, but because when you know something looks as perfect as our team originally envisioned, it’s like tasting a fine wine or beer.
The First Order Stormtrooper kit is just that. Yes, it took an inordinate span of time to create as this went through three renditions before we felt it was truly ready for prime-time.
It wasn’t enough to know that it was “just right,” we felt that it had to be darn near perfect. We now feel absolutely positive that this is the most accurate, and easy to put together armor which makes even our Classic kit look relatively complex in comparison.
So how did we do this? It boils down to these three primary focus points:
- Metal Molds
- The Power of Inversion
- Sourcing Multiple Screen-Used Suits
Why Full-Metal Molds?
To reproduce just about anything, you need to create a mold of your original piece. A mold is a hollow container used to give shape to your injected material of choice, or a solid object (often called a “buck” in this case) that can have material formed over it to create copies. There are a few ways to build a mold, and many material options to consider depending on your project.
First you need to determine how many “pulls” (or copies) you will need the mold to generate, and how to best optimize the molds to make the most use of each sheet of material.
Each mold has what is called a “pull life,” which is typically measured in how many times a mold can be used to create multiple copies of a piece before the mold degrades from overuse. Much of a mold’s life is determined by the materials it is constructed from, as temperatures and other normal wear-and-tear affect the mold’s life.
After making earlier versions of our prototype armor out of more malleable materials (to test construction, accuracy of detail, and other factors during the development process), we elected to go with a full-metal mold for our larger key projects such as our First Order Stormtrooper. The pull life of a metal mold is much longer than other alternatives, like medium-density fiberboard (“mdf”) or fiberglass, and can handle the thousands of pulls our factory required.
Metal molds also affect the final product itself! The metal surface of the mold has the advantage of retaining and holding heat during the forming process, creating smoother surfaces and better pulls due to longer work times.
Often, the shorter the work time, the greater the chance a pull will come out poorly and will need to be re-done. As one might imagine, this reduces efficiency and wastes material. Once a pull is finished, there’s no way to go back and re-use the same sheet of plastic so into the scrap bin it goes!
What is “inversion”?
Thermoforming uses air in order to suction heated, malleable plastic tightly down over a mold via a strong vacuum (hence the hobbyist term “vacuum-forming”) to create a copy. In some instances, using the traditional method of thermoforming may mean that the plastic can’t be formed tightly enough to the mold, causing the deeper corners and features to be softer looking and less defined than the original.
In the case of our First Order Stormtrooper armor, we opted for inversion casting on key pieces that require sharp detail. Utilizing an “inverted” mold forces the plastic into the mold details rather than over them, thereby creating sharper details in the finished product.
Using Multiple Screen Used Suits as Sources
Above all, this point is probably the most pertinent. The lineage of an item is unquestionably important and, in our case, we always go to screen-used pieces as reference whenever possible for scanning, photography, and documenting fine details. These are the things that make it to screen, and thus inform the most recognizable details, or those “holy grail” attributes, which when replicated bring a “right off the film” level of quality.
When we started with this project back in December of 2015, long before the release of TFA, we were tasked with creating suits for marketing purposes to be on stage for Celebration Anaheim. While the task was daunting, our source material was a cleaned up 3d print from production and not a screen-used suit. While the impression was wonderfully achieved, the source was a print that was rooted in poor scanning and reference technology. These first marketing suits were always considered passable versions that were larger and clunkier than they were supposed to be.
Nearly a year later we were given the opportunity to examine not just one, but many screen-used outfits from the film. This was extremely helpful — we could now photograph, Pantone color match and, most importantly, take our own 3D scans of multiple suits.
Having now acquired the best possible reference, we undertook the task of creating a new 3D model based on all these elements. The comparison between the previous, bulky, passable marketing trooper, and our final model was staggeringly different.
The new armor has finer proportions, and sharper detail.
Armed with this new reference, we could not only generate our own 3D model, but continuously compare our own physical prototypes to ensure faithful replication down the entire manufacturing line.The conclusion: Darn near perfection.