To unlock weapon shaping in Destiny 2, you first need to progress through the early Witch Queen campaign, then visit the Enclave on Savathûn’s Throne World and activate the Relic there. Bungie’s help page says this starts with the first few missions of The Witch Queen , which are free to all players.

Steps

  1. Go to Savathûn’s Throne World and launch The Arrival mission.
  2. Finish that mission and return to the Enclave.
  3. Speak with Ikora, then complete the Relic intro steps.
  4. After that, the shaping and reshaping system becomes available at the Relic.

How patterns work

Once crafting is unlocked, you still need a weapon pattern before you can shape a specific gun. For many weapons, that means extracting Deepsight resonance from the same weapon multiple times; one recent player discussion says most patterns require five extracts, though some weapons need fewer.

Where to do it

The actual crafting happens at the Relic inside the Enclave, not at the Tower or in your character menu. After unlocking it, you can shape new weapons or reshape eligible ones there.

Quick note

If the Relic says it is inactive, that usually means you have not finished the early Witch Queen steps yet.

TL;DR: Complete the early Witch Queen missions, finish The Arrival , visit the Enclave, and activate the Relic; then you can unlock and use weapon shaping.