This is a nano-amp-meter spin-off. The original design is on eevblog but not available for sale anymore, so I made my own, and changed a bunch of stuff, manufactured and tested.
A Professional Precision Current Adapter for Multimeters. The only low cost industry solution for multimeter burden voltage and nanoamp level current measurement.
It solves the problem of burden voltage on a multimeter. It also turns your multimeter into a powerful and precise nanoamp level measurement tool!
The best part is if you hook it to an oscilloscope you can measure/plot/store transient nano-amp current events for which you will need a really expensive logging nano-amp current meter, somewhere around a few thousand $$$$.
This is the latest design with improved specs over the original.
Have fun. Total cost is about $50 based on my experience.
Original design here, but cannot be made anymore due to obsolete components.