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In this video I walk through the process of making rings out of clear polyester resin, a type of moldable plastic. I show you everything from mold-making to embedments. I used this same technique to make my RFID rings, which are clear plastic containing unique microchips useful for electronics projects where you want to identify a specific person wearing one. Thanks to Townsend Atelier for the sample of Knead-a-Mold, a welcomed (and much easier to work with) alternative to pourable silicone for mold-making.

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Materials:

  • clear casting resin and hardener – Michael’s or other craft store
  • plastic cups
  • wooden or plastic mixing sticks
  • silicone mold-making material – Townsend Atelier Knead-a-Mold or Polytek TinSil
  • measuring cup (if using Knead-a-Mold) or high accuracy scale (if using TinSil)
  • original from which to make a mold, mine was 3D printed
  • turpentine for cleaning up unhardened resin mess
  • nitrile or latex gloves
  • dremel (small rotary tool) or sandpaper for touchups

Safety precautions:

  • Pourable silicone and craft resins emit fumes that are bad for you. Work outside or in a very well ventilated area or use a respirator, which is not the same thing as a dust mask. If you’re pregnant, wait until you are no longer so before attempting this project.
  • Craft resin is bad for your skin; wear gloves even if you don’t think you’ll spill.
  • Keep your kids and pets away from your work table.
  • Read and understand all info in the MSDS sheet that comes with these materials

Becky Stern

Becky Stern is head of wearable electronics at Adafruit Industries. Her personal site: sternlab.org


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Comments

  1. Major Wood says:

    There are two things I wish to add to this.

    1) The rings were not still sticky because they didn’t have airflow to cure them. Resins don’t air-dry like many other glues. Resins require a catalyst (sometimes called a hardener) to create a chemical reaction. The sides were still sticky because it hadn’t set long enough to cure. Most resins require at least 24 hours to fully cure.

    2) There is a highly effective way of getting bubbles out of a resin that is still pourable. Use a blow torch. Graze over the resin with a blow torch fairly quickly (at a guess, I would say about 2 inches per second) and bubbles will rise to the surface and pop.
    This is a trick that many pros use when pouring a bartop. There are also chemicals that you can use immediately after pouring to get rid up bubbles, but they often leave a haze.

  2. Becky Stern says:

    Thanks for the clarification and extra tips!

  3. Anonymous says:

    The heat might damage the mold. You should be sure your resin is designed to be used without vacuum de-bubbling. Unfortunately I think the best ones (clearest) really need to be degassed.

    There are also several brands of 2 part silicon. They all seem to work differently. There is even 1 brand safe for food use so you could cast your rings in chocolate!

  4. Austringer says:

    While preparing silicone molds for pewter casting, a trick a friend of mine came up with was to use a shop vac to degas. A container that could handle the pressure and a lid made out of an old board with a hole drilled in the middle and a conical vacuum nozzle were the ingredients in our amazing degassing chamber.

    You’re not going to make neon signs with this rig, but most of our bubbles would swell up enough that they’d rise to the surface.

  5. bekathwia says:

    Yeah, the Knead-a-Mold is food safe, and one of the recommended uses is for chocolate, yum! I agree that these could benefit from some kind of vacuum rig; I’m just trying to keep it simple. The reason I used that TinSil from Polytek is it said it was better for polyester resin than the 1:1 platinum catalyst stuff. Patti also recommended using a heat gun to help de-gas them, if your mold can stand the temperature.

  6. Anonymous says:

    non-embedded video links appear to be broken

  7. Becky Stern says:

    Fixed now, thanks!

  8. Phillip White says:

    Thanks for this post…

    Phillip White
    crazyaboutgadgets.com

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