A summary of how weapon crafting at the Enclave works.
Unlocking the Enclave
Play through the first two missions of the Witch Queen campaign. These are free for all players, and will unlock the Enclave destination and ask you to craft the Enigma, a void glaive.
If you have not started this, it should appear in the list of milestone objectives in the upper left of the director, marked by a Witch Queen icon.
After that, you can freely enter and leave the Enclave non-combat area and the Throne World.
At the Relic
The relic is down some stairs in the Mars cliff face. You craft weapons from the middle. There is an option to create a weapon, or to edit an existing crafted weapon.
When crafting or reshaping a weapon, from left to right you select the masterwork stat and tier, each weapon perk, and if you have one, an optional cosmetic Memento. As you use the crafted weapon to get kills or complete activities, it will level up. You can add different perks based on what level the weapon is. Hover over each option to see if there is a level requirement, and what materials and currencies it costs to put on the gun.
On the left side, you can pick up an inventory item called a Relic Tether that tells you how much of the crafting element you have. This is the Relic Tether’s only purpose. You can discard it and get another at any time if you need to free up inventory space.
Any legendary weapon can drop with Deepsight Resonance, meaning it has a red border and a progress bar for kills and activity completions. Filling up the progress bar allows you to manually claim Resonant Elements, a currency used for crafting and reshaping crafted weapons.
If a weapon is craftable, completing enough Deepsight Resonance versions of the weapon will unlock its pattern, allowing you to craft it. You can view your progress and which weapons are craftable from the Triumphs tab, in the Patterns and Catalysts section.
Deepsight weapons can drop from anywhere the normal version of the weapon can drop from. There are no special drop restrictions.
Some patterns require owning Witch Queen, some require a season pass, and some are free to play. It depends on where the items come from, since you need to be able to farm the item in order to unlock its pattern.