The latest TWAB (This Week At Bungie) has landed and it is a pretty hefty one that talks all things transmog (Amour Synthesis is the technical Destiny 2 term). The post has explained how the transmog system coming up in the next season, set to launch on May 11 will work, and what materials Guardians will need to acquire to be able to change the appearance of items.
The system will use a new set of materials called Synthstrands, Synthcords, and Synthweaves to be able to unlock an ornament of a former piece of armour from the Collections. Synthstrands will need to be unlocked by killing enemies, and then Synthcords can be earned by trading 150 Synthstrands into Ada-1 for a bounties to be able to get the Synthweaves necessary to unlock an ornament.
This does mean the system is a little more complex and grindy than just unlocking new armour ornaments, and to make matters a little worse, you can only unlock ten ornaments a season per class (20 within the upcoming season to help the Armour Synthesis system to get off the ground), although it does look like you will be able to buy more from Eververse (the microtransaction store). And, of course, the unlocked ornaments do only apply to Legendary armour pieces, meaning this system will not affect Exotic items.
Otherwise, the TWAB has also detailed a little more on the upcoming changes to Shaders and how when the next season arrives, a new set of Nightfall weapons will be available to earn. You can read the full TWAB that details way more information on Armour Synthesis here.