One of my players is going to be playing an Ironborn from the Book of Iron Might and he was wondering about having a construct animal companion. Does anybody know of a variant that would allow such a thing or something similar?
Clockwork Familiars might be helpful (though they are Pathfinder, it should be easy to convert) Other than that, you might want to just use a normal animal companion and change it up a bit so it is a "construct", or there could be a template somewhere.
The newly released Construct Companion, published by Rogue Genius Games also has a ton of player-centric information, including rules for construct animal companions and familiars.