Getting the Pieces
The easiest way to obtain the necessary pieces is by purchasing Lego set 7914, the Mandalorian Battle Pack. This set contains not a single Death Watch Trooper, but four, along with a speeder, a blaster turret and multiple weapons. Single Mandalorian Death Watch Troopers are also available on various auction sites and from certain Lego customization companies. If you are truly ambitious, you can customize your own trooper. The best place to start is a Jango Fett mini-figure, although any helmeted mini-figure, particularly from the Lego Star Wars line, will do in a pinch.
Assembling Your Trooper
Mandalorian mini-figures have the same functionality as any Lego mini-figure. To assemble a Death Watch Trooper mini-figure, simply snap the torso and arm section into the leg section. Next, attach the head. Finally, place your Death Watch Trooper's helmet onto its head.
Altering Your Trooper
Depending upon your starting point, you may or may not need to make alterations to your mini-figure. If you are not customizing your own mini-figure, you naturally need not make alterations. If, however, you are customizing, you may need to paint your mini-figure to ensure that its battle armor and helmet match that of a Mandalorian Death Watch Trooper. If you start from a Jango Fett mini-figure, there is minimal painting required. If you start from a different mini-figure, you will need to paint much more to ensure a match.
Equipping Your Trooper
Your trooper will, of course, need weapons and gear. Many Death Watch Troopers, especially the assassins, use a backpack-style jetpack. In the Lego universe, this pack is usually gray. The jetpack comes with the Mandalorian Battle Pack. Your trooper will also need weapons. Many Death Watch Troopers fight with a blaster (or two), a saber-style sword, or both. These Lego weapons are usually black.