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I covered British electronics hobbyist Rupert Hirst’s lovely freeform headphone amp back in December, when it was still “just” a skeletonized circuit. Now he’s finished up by casting the meticulously-constructed electronics in clear resin, with equally meticulous care. He built a custom mold from 1.5mm cardstock, carefully sealed the jacks against resin infiltration, and mounted the wire frame inside the mold. After pouring the resin and allowing it to cure, he squared up the block on a belt sander, chamfered the edges with a router, and finally polished everything up with wet/dry sandpaper and Brasso. Rupert’s aesthetic—doing relatively simple things with extraordinary attention to detail—is always inspirational to me.

Crystal cMoy Freeform Headphone Amp

Sean Michael Ragan

Sean Michael Ragan

I am descended from 5,000 generations of tool-using primates. Also, I went to college and stuff. I am a long-time contributor to MAKE magazine and makezine.com. My work has also appeared in ReadyMade, c’t – Magazin für Computertechnik, and The Wall Street Journal.


  • Travis

    ooooh…Beautiful
    I just wonder (slightly) about heat dissipation and thermal expansion/contraction. I suspect in this circuit it may not be much of an issue at all, but in something more complicated probably could be.

    I might have to try this technique with a thumb drive.

    • http://pltw.nmsu.edu Daniel Kim

      I use a very thin micro-SD to USB adapter. The business end of this adapter is covered with a thin sheet of plastic which breaks after being used for a month or two. Now, when I buy an adapter, I pry the case apart and fill the space behind the thin plastic sheet with epoxy resin, then reassemble it. This makes them last much longer (actually, I haven’t had one break yet).

  • bdaniel7

    Don’t the electronics need some cooling? And what happens when one of them gets burnt for some reason?

  • Lars

    Resin also conducts and spreads heat. Of course, there’s an upper limit to the application…

  • http://www.facebook.com/brannana Andrew Brannan

    But, according to the Maker ethic, one he finishes it, he no longer owns it. I mean, he can’t open it, right?

    • Sean Ragan

      That’s exactly correct! Now it belongs to me. You did read the fine print on the mint tin, right? =)

  • http://pltw.nmsu.edu Daniel Kim

    Looks a lot like an agarose mini-gel rig
    http://www3.bio-rad.com/cmc_upload/Products/-19492/61406.jpg

  • Evan Foss

    That is totally unserviceable.

  • jamesbx

    I’ve seen mechanical samples (electric motors) potted in optically clear epoxy, sliced in half on a bandsaw, the similarly polished to create a cut-away view. As with this project, it turns something mundane into a display worthy object of interest.

  • Chris

    Based on the aesthetic, one is inclined to suppose that this Rupert Hirst is related to Damien Hirst.

  • John Joseph

    When I was a kid (Late 60’s) I found some military surplus avionics that were encased similarly in resin and had a male type plug on one side. I thought they were pretty cool then, this beautiful object reminds me of one of those.

  • Walter G

    What specific resin did he use to pot this? Excellent clarity and very few bubbles (I think I spotted a few), very good wetting job! Would love to hear his technique for potting!

  • http://www.facebook.com/craig.hunt.161 Craig Hunt

    The Bride Stripped Bare!

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