4mm Plugs
In my job as a college electronics technician I use 4mm plugs regularly for making test leads for the students and myself I like these plugs as they are very reasonably priced and seem pretty relaiable.They can be a little tricky to solder as the plug needs a fair bit of heating to get to soldering temperature. I plug them into a row of 4mm holes drilled into some scrap mdf board to hold them steady while I heat them. As wood is a good thermal insulator you don't lose much heat by conduction away from your soldering iron.Don't forget to put the plastic body of the plug onto the cable before soldering!