Ok, well the other day i grabbed a deal on ebay - a resin model of the season two gun from battle star galactica! it cos me only 16 Pounds which is considering that the cheapest Ive seen them is 40 Pounds.
It was basically a sand and paint job. Firstly i took my dremel to it to sand off the rough 'seam' lines. I also deepened the barrel holes. Once this was done i then filled in an gaps (formed by bubbles normally) with epoxy resin, and resanded those areas.
I then gave the whole model about 20 thin coats of black spray paint, I added further detail using silver leaf paint to the switches, and brown to the handle.