Lost Wax Casting, ancient technology, still in service

The process goes like this.  Make a wax version of the desired part or artwork.  Then cover the wax master  with clay.  The clay was fired (like pottery) to make it hard and tough.  In the firing the wax melted and ran out.  Then molten metal was poured into the clay mold and allowed to cool and harden.  When cool, the clay mold was broken off and you had a shiny new part or art object.  And no mold parting marks.  Aviation Week claims the lost wax process is 5000 years old.
   Today we call the process "investment casting"  and a lot of key aerospace parts are still made that way.  In fact Aviation Week was complaining about a lack of investment casting capacity  slowing production in the aerospace industry.   One key part made by investment casting is the turbine blades for jet engines.  The tougher you can make the turbine blades, the hotter you can run them which gives better fuel mileage, which translates into better range and better carrying capacity.  Modern turbine blades are very tricky, they have cooling passages up the center, they are cast from secret alloys involving a lot of nickel, and who knows what else, and they are cooled slowly and carefully so that they come out as single crystals of metal.  Some one commented "There are nine countries in the world that can make nuclear bombs, but only two, the US and the UK, that can make modern jet engine turbine blades."