Sectioned Armor is a masterwork suit of Full Plate that can be stripped down partially into medium armor or fully into light armor. If anyone wants to look at its stats, check the 3.5 Planar Handbook. Because of the uniqueness of the armor, one has to think how exactly a character dons and removes it. This is my effort to make a design that hopefully works and makes sense. Any critiques are welcome and even encouraged!
Because Sectioned Armor must be masterwork quality to begin with and already costs twice as much as regular Full Plate, it seems reasonable that the sections can operate under the Quick Escape mechanism put forth in 3.0's Arms and Equipment guide. The wearer can use a standard action to spring a lock on the armor and immediately drop the full suit.
With Sectioned Armor, it doesn't seem much of a stretch to think each section could operate like that too, with some modifications. Dropping one section takes a standard action. Dropping two, however, should take a full-round action since the combination really ought to be a move+standard. Dropping the full rig would take a full round plus the wearer's swift action for his next turn.
Donning full Sectioned Armor, under the rules of Quick Escape, would take 8 minutes and require help for the full benefit. Because of how modular it is though, I'd wager a character proficient in the use of heavy armor could cut that down to 6 minutes, without help. Each section would take two minutes. With help it would take three minutes to fully don, one minute per section. Essentially it takes 1.5x as long to don this particular piece of gear because of piecing it together.
Special note: Sectioned Armor works a little differently when given the Called enhancement. Because of the armor being modular, the character can don any number of sections as a Standard action. If already wearing partial armor of the same suit, the character may Call extra pieces on as a Standard action, up to the maximum of three sections equaling Full Plate. To drop the sections, one should consult the rules mentioned above or perhaps add a synergy to Called to make the armor or shield appear able to be dismissed and appear in a given bag or special location on the same plane.