Harwin M20-1060100 available from Farnell and Mouser
The way I make test leads of this type is to solder insulated wire into a suitable crimp contact, e.g.
https://www.harwin.com/products/M20-1160042/ and then use heatshrink tubing for strain relief and insulation over the contact body. Every few years I buy a reel of 1000 contacts (usually a Molex part) for this purpose.
For the wire, I typically use leftover ribbon cable, either conventional or twisted pair. PVC insulation on cheap ribbon cable means you have to be careful and quick when soldering it, but with practice it is not a problem.
This makes for cheap test leads when prototyping.