Haven't seen anyone set one up, so I thought I'd go ahead and start.
So currently, I'm building my engineer around the Flamethrower and Elixir Gun. Having just hit 40 earlier, my build currently looks like this
but ultimately I'm aiming for something like this (talent calculator is slightly out of date I think)
with Energized Armor (5% of toughness is converted to power) in the first tier of Inventions (in game this is fine, the calculator doesnt have it till second tier). For the last Tier of alchemy, I'm not 100% sure yet, but I was thinking Backpack Regenerator (in game it says kit, not med kit). Regen on kit switch is rather useful I think.
So the idea behind building this way is damage up front with the Flamethrower, and support from behind with the Elixir Gun. Its a rather tanky build, but it also brings a lot of boon support and healing. Juggernaut in the third tier of Firearms combined with Energized Armor from the first tier of Inventions looks to be a good combination, giving me an extra boost of damage to the already upgraded Flamethrower. With the Elixir Gun equipped, I then get increased range (meaning I can stand out of harms way) place down aoe healing and remove conditions, which so far has been looking quite useful in WvW, especially during a zerg. Also, With Elixir H and Elixir B I can provide further boon support. Elixir X is really only there because I love becoming a tornado (that and I havent played with very many of the Elite Skills yet).
So fellow engineers, what do you think? What kind of way are you building your characters? What is your favourite gadget? Discuss!