I'm no longer using lost-wax casting in my own work, but here's this page as a public service.  I used to do more of it back when I was working like this, using 3D-printed models instead of wax models.

The lost-wax method is mature technology.  It has been used by many cultures since before the beginning of recorded history, and it's as close to perfected as a sculpture technique can be.  The method is wonderfully flexible, and a good foundryman can use it to cast very complex designs in one piece.

It works like this:

Start with a wax or plastic model.	Mount it on a wax rod called a "gate" (or if there's more than one, a "sprue").	Suspend it in a cup ("flask") and pour heat-resistant plaster around it.	The plaster ("investment") hardens to form a mold.
Heat from a kiln first melts the wax out of the mold, then vaporizes the residue.	Pour molten silver (gold, bronze, platinum...) through the gate into the mold.	After the metal cools in the mold, break the investment off.	Cut off the metal rod left by the sprue, and there's your piece in metal.

It's called "lost-wax" because the original model is destroyed by heat, and notice that at the end of the process, the mold is destroyed too.  So at the end there's only the metal: to make a second instance of a sculpture, or an edition, it's necessary to start all over again with a new model.

Most of this process is usually done by a foundry -- I for one am not really clever enough to do my own casting -- but afterwards there's more to do: the casting as it comes out of the mold is rough and warty with air vents and sprues, and usually looks more like scrap than like art. 

At right is a rough casting of AlterKnot, as I received it from the foundry.  This is a very good casting with clean metal everywhere.  At lower left you can see the stub where the main gate was cut off; at the top and lower right are smaller stubs where air vents were, along with supports to keep the model from warping and breaking.

All these need to be finished off and retextured to get to a finished casting, and I'm very glad not to have to do this anymore.