PCL melts at low temperatures. Photo: cc-by-2.0, Steve Jurvetson

PCL melts at low temperatures.
Photo: cc-by-2.0, Steve Jurvetson

One of the coolest materials for making is a moldable plastic called Polycaprolactone, or PCL. You may have seen it marketed as Shapelock, PolyMorph, InstaMorph, ThermoMorph, or other brand names.

PCL is typically sold in small round pellets. The pearly white material melts at about 140 degrees Fahrenheit (60 degrees Celsius), and becomes transparent and pliable as Silly Putty. Then you can shape it however you like, and it can be re-melted and reformed many times. Once hardened, PCL can be cut, drilled, filed, or worked in any number of ways. This makes it perfect for making prototypes, performing repairs, and making all sorts of customized stuff.

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While I’ve seen many cool things made with PCL, some of the most creative techniques I’ve heard of were developed by a friend of mine, Gareth from Let’s Make Robots. Gareth developed a series of workshop posts showing how to form useful shapes, add color and more neat stuff. Another Let’s Make Robots member, Russell, posted a tip on how to make sheets and brackets from PCL.

The links for all of these posts are below, so go check them out and give PCL a try.

Andrew Terranova

Andrew Terranova

Andrew Terranova is an electrical engineer, writer and an electronics and robotics hobbyist. He is an active member of the Let’s Make Robots community, and handles public relations for the site.
Andrew has created and curated robotics exhibits for the Children’s Museum of Somerset County, NJ and taught robotics classes for the Kaleidoscope Learning Center in Blairstown, NJ and for a public primary school. Andrew is always looking for ways to engage makers and educators.

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  • kongorilla

    A warning (copied from my comment last time PCL was mentioned on this blog): PCL starts out very strong, but over a period of years becomes very brittle. I made many items with PCL (the Friendly Plastic brand) in the late 80′s and early 90′s, and all of those items subjected to ANY force crumbled to bits within 10 years or so. Similarly, the unused pellets no longer melt completely anymore, and when they harden, they’re a brittle, flaky mess.

    So, this stuff is great for prototyping and having fun, but don’t make anything you want to last or is stressed for a long time.

    • http://ignoblegnome.blogspot.com Andrew Terranova

      Thanks for the comment. Nothing I’ve made from PCL is that old yet, so I haven’t run into any issues. I did have one set of robot parts melt on me when I left them in a hot garage during the hottest part of the summer.
      PCL is certainly not perfect, but it is great stuff for a lot of uses.

      • kongorilla

        I see on Amaco’s own site (they make Friendly Plastic brand PCL), the issue of shelf life is addressed, at least vaguely. Check under “Purchasing, Storing and Reconditioning”.

        Back in the day, I tried everything to “recondition” the pellets (the tub of pellets was very expensive), and nothing worked, including what is recommended by the article.

        They only address the problem of working with old plastic. They don’t mention that your finished creations are vulnerable as well. I had done elaborately sculpted animations for my 3D zoetropes, and ten years later all I had to show for all my work was armature wire and plastic rubble. I hope all the PLA I’m printing these days fares better.

  • David Mc

    I made a plaster mold of my robots face and then pushed some melted PLC into the mold.
    I worked very well and I only replaced it after I made a 3d print that was the exact shape I wanted. Still have the PLC head and it never got brittle.
    It is amazing stuff.