Sketch out the finished sculpture you are envisioning with a pencil and paper. Your armature will serve as your sculpture's skeleton, so it is important that you plan ahead what you want your sculpture to look like. If you make mistakes with the armature, making one part too long for example, they will be very difficult to correct later.
Measure out three long pieces of bundling wire and cut them with the wire cutter. You will make your skeleton from this wire.
Twist the three pieces of wire together with a pair of pliers. You need to wind at least three pieces together because the skeleton needs to be strong enough to support your sculpture. The ridges between the wires will also give your clay or sculpting material something to bite on to.
Bend the entwined wires into the shape you want your skeleton to be. The shape doesn't need to look perfect; don't try to form wire details like hands, for instance. It should be the same proportions that you want your sculpture to be, though. You can add more wire if necessary, use multiple strands of entwined wires, or trim some off if you need to. You should end up with a wire skeleton the same size that you want your sculpture to be.
Drill holes into the wooden base where you want to attach your wire skeleton. For example, if you are making a person, drill two holes into the base to insert the feet into. You can use any type of wood you like for the base.
Insert the bottom wires, the feet on a person for example, into the holes in the base. Fill the holes with wood glue and allow the glue to dry completely.
Adjust your skeleton to stand exactly the way you want your sculpture to stand. Add a 2-part epoxy putty to any part of the skeleton, the torso or head for example, that you'd like to bulk up if you want to. Allow the epoxy to dry before you begin sculpting.