[D&D 3.5] construct feats

[Karnith]

There is a feat that allows crafting normally mindless constructs with Intelligence score (though nobody said it will be good Intelligence score). I don't remember the name, though, and it is probably Dragon Magazine material.

It's Rudimentary Intelligence, in Dragon Magazine #327, p. 73. It costs 8,000 extra gold and grants the construct an Int score of half your CL without interfering with the control you have over the construct.

Ideally the process would grant a feat without giving the construct an intelligence score, to preserve the construct's mindless nature, and therefore its immunity to mind affecting effects and the total loyalty that a mindless construct has for its creator. (I'll edit this into the OP)

Constructs have immunity to mind-affecting effects regardless of whether or not they are mindless; it's a feature of the Construct type.