Zapthrottle Mote Extractor
Another one of the ways to make money with engineering is the Zapthrottle Mote Extractor. This handy device allows the engineer to see gas clouds on the mini-map. Unlike other resource nodes, gas clouds are mobile so sometimes you must wait for them to travel out of an unreachable area to a more accessible area. When you extract from the gas clouds, you will receive 3-5 motes or crystallized eternals depending on which cloud you are extracting from. These gas clouds are numerous and the low population of engineers makes for less competition. Here is the list of where to find the various gas clouds and what they produce.
Felmist - Shadowmoon Valley - Motes of Shadow
Swamp Gas - Zangarmarsh & Steamvault - Motes of Water
Arcane Vortex - Netherstorm - Motes of Mana
Windy Cloud - Nagrand - Motes of Air
Steam Cloud - Sholazar Basin & Borean Tundra - Crystallized Fire & Water
Cinder Cloud - Sholazar Basin, Wintergrasp, & Dragonblight - Crystallized Fire
Arctic Cloud - Howling Fjord, Dragonblight, Storm Peaks, & Icecrown - Crystallized Air & Water
So if you are an engineer, make sure to complete your quest to create your extractor and carry it with you at all times. My favorite spot to farm Crystallized Fire to create Eternal Fires is at the Cauldren of Flames in Wintergrasp where you can kill the revenants and elementals as well as pick up 2 cinder clouds in the same area as well as a titanium node. Then while waiting for respawns, I fly just below into Dragonblight and grab the Cinder Cloud outside the Obsidian Dragonshrine and the Arctic Cloud towards the Wrathgate and loop back to the Cauldren of Flames.
Do you have any great spots that allow you to access the clouds while farming other things?