Another spring-loaded test Pogo pin - this tip would be particularly useful for making devices that run into each other and you want to electrically link them.

The cup on the tip would be ideal for receiving a pin of some sort. The cup measures 1.5mm (0.59") in diameter, the outer shaft diameter is 1.01mm (0.040"), and overall uncompressed length of 33mm (1.3") with 6.5mm (1/4") travel.