For my DIY hub dynamo charger (which I use to power and recharge my GPS and/or phone while I ride bicycle) I needed some spare plugs for attaching the wires to the hub dynamo. These are not so easy to get, and if you do, they are rather expensive - so why not 3-D print them on my RepRap??? Here is the result - which I found to work just as nicely as the original plug.

The plug consists of an inner part and an outer shell. The stripped wires are pushed into the holes of the inner part and bent around (as shown on the photo) before the inner part is pushed into the outer shell, squeezing the wires for a firm hold. (The last photo shows the original plug.)