I guess Artificer is just too easy
Sorcerer/Wizard->Effigy Master + Craft Construct?
The Effigy Master stuff basically would give you to ability to make a giant robot version of any type of creature except Oozes, Undead, & Plants and I think Constructs too. Craft Construct just filling in the Construct part then.
Probably even some Rogue dip for on site tinkering stuff via disable device & trapfinding & UMD for nonarcane stuff.
There's that Battlesmith PrC, but I think that's dwarves only, if you want a little 'umph' to your character and not just be a crafter hanging in the back.
Warlock would also be a decent one, but not till that level 12 class feature, that can craft anything you want so long as you got the crafting feat and still handle well in a fight or utilize his easy escapes for some "I'LL GET YOU NEXT TIME SONIIIIC!!"