The military didn't authorize the construction of the Gundams, only the Leo, Aries, Virgo, Scorpio, Pisces, Cancer, Taurus, and Tragos... and those are all standard mobile suits. Gundanium can only be refined in space on the resource satellites, so it isn't something that can be mass-produced in large quantities, but at the same time, it's strength and heat-resistance is stronger than that of titanium and it's non-conductive and undetectable through radar. All of that makes it ideal for a giant weapon of mass destruction but less than ideal for something that needs to be produced en masse.

[ Not that it answered Hiro's question. Like, at all... but that's what he latched onto. ]

How are you with the construction of an item from a blueprint?

[ He found himself a toy while trying to do some minor tweaking to ZERO, but while he could probably pull it off on his own, it might function better if he had assistance. ]