seam-ripper meter.jpg
If you use conductive thread in your projects, then you might want to check out this tutorial for making a seam ripper that also tests the electrical path of conductive thread by instructables member Plusea.

This seam-ripper has a continuity meter built in. An LED lights up to indicate when an unwanted electrical connection is made between the tip of the seam-ripper and the part of the circuit that you wish to disconnect from. An alligator clip can be connected to different parts of the circuit, so that you can decide where to measure for unwanted continuity. The LED is powered by a 3V coin cell battery. The brighter the light, the less electrical resistance.