This rebel transport's captain was irritated that he had no defence against TIE fighters, so he scrounged up 3 dual heavy laser cannons and mounted them accordingly, and since then he has not had a problem with TIE fighters.

The kit is from the Star Wars Hoth Hangar. and is pretty much built straight from the box, with the cannons coming from a USS Arizona kit and a sensor array from a X-wing Laser. Scale of the kit is about 1/160-1/200.

Image: Underneath