I am playing level 2 artificer and looking to create some Arbalester constructs. I am looking for a way to give them the ability to fly, and I'd like to be able to give them flying by level 4 at the latest. Not for the purpose of recreating the US Airforce, but to allow them to operate outside of melee range. A specific situation I am looking to create is a guardian turret protecting a dungeon room behind us so we don't have to worry as much about having enemies coming up behind us.
At level 4 it is impossible unless you somehow get the Craft Construct feat before level 4.
At 6th character level (with at least 4 levels of artificer) you'll have a feat and access to the craft homunculus class feature (or earlier if you somehow get a feat). With both you can get the feat Improved Homunculus.
Improved Homunculus (Magic of Eberron, pg. 49).
Prerequisite: Craft (any) 6 ranks, Craft Construct or craft homunculus class feature.
(...) If you use the craft homunculus class feature of the artificer class, your homunculus gains natural armor and special abilities based on its current HD, and additional natural armor or special abilities if you later increase its HD.
You improve your homunculus until it reaches 3 HD and he can choose one of the abilities described in table of this feat, one of them is Flyer.
Gains fly 20 ft. (good) or existing fly speed improves by 20 ft. and maneuverability improves by one category.
To upgrade an Arbalest to 3 HD, you'll spend 4000 gp and 320 XP (You can use your craft reserve here). Your homunculus will be an 3 HD Arbalest with +2 natutal armor and Flyer thanks to your Improved Homunculus feat. The more you upgrade your homunculus, it will get more natural armor and more special abilities.