Engineering at the expert level breaks into two disciplines: gnome and goblin.  While I think it is a waste, you should be aware of gnome specialization.  They make items and gadgets that claim to change the world, but rarely often work.$B$B$N, read this manual.  If you wish to learn how to make metal paper weights, then take that manual to Tinkmaster Overspark in Ironforge.   Remember - membership is permanent and prevents joining the other discipline, so make sure you are sure before finishing his task!