The testpen

Once again, when you need a test pin you can print this and save your money.
Gain the idea is to use a paperclip for your metallic tip, solder on a cable that can be threaded through the slit on the pin side. A drop of glue in the slit or heat to burn the paperclip in place and you have an isolated test pin..

Should be printed with a raft so it stands still!