GM328A 1.20 3D printed case


I bought the GM328A v1.20 2015.05 component tester in Oct 2016 for the price of 18.98€ – there were no cases available for it back then.

You need to get your fingers very close to the component tester to fiddle with its controls. Having it in a standard plastic box would reduce this accessibility.

3D printed case

In 2018 there were already some 3D case designs available for GM328A on https://www.thingiverse.com/ so I chose one model and sent an email to a local company advertising 3D prints. However, the anticipation was short lived, the quote was exorbitant, more than the price of the tester.

Fast forward few more years, I now own a 3D printer and I needed the component tester for some projects; it started itching again for a case. Went back to Thingiverse to look – but they are the exact same old cases, blocky rectangular ones that would reduce the ease of use of the tester.

Switch my attention to Google Image searches, and after a LOT of scrolling to the point I was giving up and considering doing my own, I hit jack pot.


Jan_P has created a very thoughtful 3D case, I immediately knew this is the one. I set the printer loose on chewing the .stl and after 6 hours, this is the result:

The rubber feet are a must, otherwise when you push down on the TEST button the box will run away.

I am worried about the battery being connected all the time – what if in one year I take the tester out and discover the battery is empty ? Thinking to calculate how long with the 9V battery last always connected, I tried searching how much current the tester uses in sleep mode. Various GM328 devices are advertised as using less than 20nA. Indeed, the current is not even registering on the μA scale of the the meter. This means that a 400mAh 9V battery will last 2 years. Still annoying.

I will be on the lookout for a small ON/OFF button that I can afix to the case.

Few more photos during the print:

Thank you to Jan_P for this very nice 3D model 🙂

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