I assume that You are talking about checking Capacitors for Leakage-Current.
The Capacitance measurement part is easy,
but Leakage requires some very sensitive measurement.
"Mr. Carlson's Lab" on YouTube, has Plans available for an extremely sensitive DIY Leakage-Tester.
You will have to become a Patrion of his Channel to gain access to all of his various DIY-Plans.
It's worth it, and cheap, it's a top quality Electronics Channel. https://www.youtube.com/channel/UCU9SoQxJewrWb_3GxeteQPA
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