Snake has a base in Metal Gear Solid: Peace Walker. By using the Fulton Recovery System players can find staff members to work in an off shore rig. Each Mother Base staff member has individual attributes and they can support Snake by adding functions to the base. One of the functions is weapon development. Snake can upgrade weapons and create new ones at Mother Base.
When Snake enters the field he will run into AI Weapons, giant robot adversaries that can sing with Vocaloid voices, the same technology that makes Hatsune Miku. Metal Gear Solid: Peace Walker has airborne, hover, and tank-style vehicles to fight.
Here are renders of the AI Weapons and have plenty of screenshots of Snake in co-op missions and pictures of Mother Base. Check them out below.