Opposable Thumbs is a podcast where Rob Ray and I solve a different design challenge every two weeks. Each episode features a guest with a different creative background, and each guest picks the challenge for the next episode. You can listen to all of our episodes here.

Homemade Chemicals! For this episode I revisited the idea of etching my own circuit boards, which I’d previously attempted (and failed). I watched/read a lot of cool tutorials online, then settled on this one. Sylvia’s Super Awesome Mini Maker Show was also a strong influence. Man, I can’t wait to get my kid into that kind of next-level nerdery…

I think my previous failure was due to old chemicals. All this ran about $25, but you could probably make it cheaper depending on what’s laying around the shop. I also made a little more volume this time: 2 shots acid and 4 shots peroxide (though that may be a glass votive candle holder, YMMV). I researched my gloves and bucket composition to make sure I didn’t create a Breaking Bad situation. I also wore wraparound goggles and pants, though I did wear short sleeves – nobody’s perfect. I suppose I should put a disclaimer here: try this stuff at your own risk, do your homework, and be careful! Muriatic acid is no joke.

This process etched a credit card sized board in about 10 minutes. The etch moves faster as time goes by, and you could almost watch the last 10% dissolve in real time. The solution is supposed to keep indefinitely, and can be refreshed with more acid and/or peroxide. See the link above for details.

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