Yoctopuce Yocto - Amp
This sensor device is a digital USB ammeter that allows you to measure current automatically. It can provide quite precise digital measures: 2 mA, 1%. It works with direct current (DC) as well as alternating current (AC) for which it provides the RMS value (5 mA or 3%).
The sensor device is isolated: the sensing part is electrically disconnected from the USB part. This means you can measure any current including from the mains, without risk of frying your hardware.
You can use this long, thick enclosure for housing this sensor.