From Halopedia, the Halo wiki
Design patterns, commonly known simply as patterns, are templates used by the Covenant and its remnants to make and classify the numerous different types of their technology. Design patterns comprise instructions fed to nanomachines that construct Covenant machinery. Many patterns are based on the analysis and replication of Forerunner technology; however, improving or substantially altering the work of the "gods" was heavily restricted by the Prophets.
Sangheili harness patterns
The Sangheili Commando harness' helmet pattern for the Commando Unit formed in 2552 was based on a pre-contact ground forces pattern with upgrades that include hardened communications gear and uplink capabilities.
Infantry weapon patterns
During the Human-Covenant War, after Human snipers showed that pinpoint firepower could throw entire armies into disarray, Particle Beam Rifle patterns were quickly selected. Despite this, the Covenant do not distinguish the various Particle Beam Rifle patterns from one another, and simply group them together based on core components and intended use.
Needler pre-Covenant design patterns use Subanese crystal in interesting but poorly understood ways. Sangheili artisan-armorers were researching to unlock the crystal's secrets after the fall of High Charity.
The Brute Plasma Rifle was made when the artisan-engineers in the Prophet of Truth's employment were allowed to modify the Plasma Rifle's sacred design pattern to suit the nature of the Jiralhanae.
The design pattern of the Plasma Pistol was reverse engineered from a Forerunner tool of indeterminate function, which was standardized and blessed for full-scale replication.
There are several patterns of Plasma Pistols, most of which are grouped under the Type-25 Plasma Pistol label, and with the loss of High Charity, Plasma Pistols started to appear with numerous cases and variants.
Vehicle weapon patterns
Ship specification patterns
Ship armament patterns