The Portal Turret is a pretty minimalist object but it still has a number of complex details. The Guns on the original version vary greatly from those on the Turrets in Portal 2. I chose to stick with the simpler and more iconic design of the Portal 1 Turret, which has a stubby cylindrical gun above a longer, more pointy gun. At this point I had completely given up on making the gun-pods pop out, even though I had somewhat figured out how to make them retract into the body. In the end I just turned some sections of dowels on a hobby lathe and attached them with friction fit pegs. The same product could probably be created using a belt-sander and hand drill, but use whatever is easiest.
At one point I had planned on mounting disposable camera flash components inside the barrels of the guns to give the effect that they were actually shooting, but the final product is almost entirely devoid of electronics.