simple molds

These are 2D "sandwich" type molds. They were designed in-house and cut for us by an on line metal fabrication service.

One of the issues that we have at the TybeeCleanBeach recycling workshop is the issue of what to make. Our machines are comparatively small, low-volume, low pressure affairs. This means the items that we make are going to be fairly simple.

We also want to break the mindset that plastic is a "use one time, throw away" material. The landfills are full, and burning it isn't very environmentally conscious. Plastic has a long lifespan, and we want to make things that will last and be used for a long time as well... making more plastic spoons is not our mission.

So what we started with were a few of the Precious Plastic designs for sea animal outlines, a coaster, and a square flower pot. Since then, we've expanded to include letters and numbers, and most recently, soap dishes, round flower pots, and small beads for craft projects.

This brings us to the problem of molds. Right now, we use two primary types of molds- stacked molds and true 3D molds.

The "sandwich" type of molds are the simplest. Described in simple terms, these consist of a top plate with some form of injection point, a bottom plate which is usually solid, and a middle plate containing some form of outline. The results of this type of mold- with exceptions- is basically a 2D shape of a consistent thickness, with some kind of outline. For example, our manatee mold is a 2D outline of a manatee. We make these into necklaces, keychains, and fridge magnets.

The exception is our coaster mold, for example. These have a dedicated bottom plate with a shallow, solid circle welded on. This becomes a depression where your glass goes. On the other side, we have a thin laser-cut plate with "Made from recovered plastic, TybeeCleanBeach.org", and then the top plate. 

These sandwich molds are comparatively inexpensive to make- we use both a local waterjet company and an online service to do our cutting for us. I have a diode laser engraver that I use to proof the designs. While I suppose that it would be possible to design molds without this step, it greatly improves my confidence level when I can hold up a cardboard mockup of a mold before we commit the dollars to have it cut from metal.

The other type of mold is a true 3D mold. These are much more complex to design, and expensive to execute. We have a few that we got from Sustainable Design Studio, and they are beautifully made and make an excellent product. When we one day get a grant for a gazillion dollars, we'll have them design and make all our molds... they really know what they're doing.

Even so, these molds are nothing compared to the high-pressure molds used by the plastics industry. It's not uncommon for a professionally made mold to cost ten to twenty thousand dollars. As Sir Alec Guiness said in Star Wars, "These aren't the molds you're looking for." Or something like that, it was a long time ago.

So molds are a big part of any plastic recycling workshop. We spend a great deal of time thinking about molds. Often it's the determining factor when we decide on a new product- where will we get the molds?

​We'll talk about them in more detail in upcoming posts

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A 3D soap dish mold, provided by Sustainable Design Studios. These are much more complex and expensive, but they work really well.