In Issue 40 of the Star Wars Insider as well as in Episode 5 of Lynne's Diary on the official Star Wars site we are given our first official glimpses of this blaster.
The Royal Palace Guards carry these specially customized heavy multi-purpose pistols. For special circumstances, these blasters are equipped to fire a grappling hook and cable. Naboo forces prefer non-violent solutions, but when violence is unavoidable the Guards wield this weapon with skill.
The base gun is the Beeman / FWB C55 air gun as pictured below. The compressed air tank was removed from the gun and a small cylindrical piece was added just below the very tip of the barrel...other than that the basic gun was hardly modified. The main scopes for the gun were all custom machined (probably of aluminum) and attached to the gun with custom mounts. While the detail piece added under the barrel could be custom machined we believe it may be a real part of something from the same medical supply warehouse spotlighted in Lynne's Diary.
In the clip from Lynne's diary below the guns were actually resin castings from a "master" blaster. (I know....Master Blaster rules Thunderdome!) Once cast the guns are then painted so as to look as close to the real thing as possible. It is obviously cheaper to make resin castings of the gun than to spend $2000 on real guns for all the background characters.
A "knob" as pictured above is attached to the side of the gun's grip and slides into a clip worn on the belt. By design, the props remain free to pivot within the clips and are released simply by pressing two arms on either side of the clip. These clips, originally, are from Covertec a European manufacturer of protective cases for PDAs, HPCs, mini-notebooks and cellular phones as can be seen in the photos below.
Covertec Belt Clip