Other than the helmet, one of the features we viewed as a "must have" item for the suit was the forearm missile. Much like the helmet, the forearm missile gauntlet has some really tight packaging. There was also the issue that in the film when the gauntlet opens it's done as a visual effect (as are most all of the suit functions.)

 We had seen other missile compartments that people had done but they usually only had the top open- we wanted the sides to fold down as well. The other thing we wanted was for the missile pod to open up and back, just like in the movie. And we wanted the missile to extend outward- in for a penny, in for a pound!

To make the opening compartment the fiberglass gauntlet was first cut apart into the appropriate sections and a plastic base plate was epoxied into the opening. Each of the cut side panels had a 4-40 screw epoxied onto the inside forward point using Propoxy 20. Onto this screw was fitted a swivel link with a rod that was epoxied into the forward section of the gauntlet. This formed a very simple single pivot hinge for the front of each of the side panels. 

To make the side panels fold down two sub-micro servos had their output arms fitted with a small section of bent music wire that was epoxied to the back of each of the side panels. The servos are attached to the base plate using high strength Velcro. As the servo arms rotate the side panels drop down. A very simple and reliable system.

The missile housing was constructed using thin birch plywood sheet. To make the housing move up and back a small parallelogram linkage was fabricated and attached to the micro servo that raises the housing. The servo is attached to the gauntlet base plate using high strength Velcro. The forward hinge uses a 4-40 ball link attached to the plywood housing and the rear link uses music wire that pivots in brass tubes epoxied to both the servo and the plywood housing. The face of the missile housing was built up using Apoxie Sculpt.

The missile is moved forward in the housing by a sub-micro servo with a long arm. The servo is mounted to the underside of the pod and the arm extends through the bottom of the pod. A short length of music wire is attached to the servo arm and goes through the back center of the missile so as the servo arm rotates the missile extends and retracts through the pod opening. The missile is a short length of wood dowel sanded to shape. 

The AA battery holders are held underneath the base plate along with a power switch and an Ethernet connector. The connector is mounted to a small PCB with connectors for the servos and it also has extended wires that reach the gloves. A Ethernet cable runs from the Arduino in the back of suit, down the arm and then connects to the gauntlet. This cable carries the signals for the servos as well as signals and power to the RFID reader in the glove. 

That's a whole lot of hardware in a very small space. Believe it or not his arm fits in there no problem- the opening is a lot bigger than it looks in the photo. The gauntlet worked perfect right out of the gate, which was awesome.