The Action Figure Biomechanical Research Facility (hereby referred to as AFBRF) works toward the improvement of plastic representations of soldiers, by integration of parts from differing families of fighter, and the use of various structural and cosmetic modifications.
The primary stock with which AFBRF works is the GI Joe, due to its modular composition and high quality construction. The GI Joe form factor has been copied by other, lower quality factories, with the result that specimens from these factories make ideal sources for raw materials to modify and implant into GI Joe subjects. They are also far less expensive than authentic GI Joes, and therefore lend themselves far better to mass acquisition and experimentation.
Tools
Double headed screwdriver. These are generally found in computer repair kits now, but were often given away by gas stations as promotional pieces in the past. The pen-sized ones are the perfect size for figure modification.
Soldering iron. Useful for direct modification and deformation of figures (adding third eyes, battle scars, gun mounts on shoulder, etc.) The standard GI Joe plastic is higher-temperature and more resistant to soldering iron work, so for extensive modification, use of lower-quality items is recommended.
Utility knife. Both small, scalpel-like knives and larger models are helpful for sculpting purposes.
Paint markers, both metallic and other colors. These are useful after all modification is complete, and cosmetic alteration is necessary.
Basic anatomy
The GI Joe form factor is very simple- the body is held together by a flexible rubber cord, which is bent around the central strut of the torso (accessible by use of a Phillips head screwdriver on the screw in the back. The access hole for this screw generally serves as a backpack/accessory mount for GI Joes.) The other end of this cord is attached at the pelvis, by means of a metal hook.
Once the central strut is unscrewed and the torso opened, the cord can be removed, and the body split into its component pieces.
The head is attached by a simple ball and socket at the top of the torso, which allows free rotation of the head.
The outer pelvis is a cover piece protecting the pelvic cord attachment hook, and providing necessary resistance for the legs to be positioned (without this piece, the legs would simply flop around.)
The arms are mounted on the torso by means of a rotating joint. Further disassembly of the arm once removed is quite possible, but not recommended due to the nature of its construction.
Recommendations
Swapping heads is the simplest modification, and often gives amusing results.
Take armored GI Joes apart and swap single arms from them out to other GI Joes to create a cyborg. You can also deform the head with the soldering iron and use paint markers to make the area metallic, as well as to give the finished product Terminator eyes.
Guns can be cut up with the utility knife and combined for more fearsome weaponry, or implanted into the figure itself.
The possibilities are limitless!