Find a token's burn address
Every letscash token already has one, and it can receive ETH before anybody pays to deploy the vault.
Fund a vault from here
Prepaid
Send ETH to the address; it splits and burns down over the schedule. No permission needed.
Perpetual
Point your token’s fee stream at its vault and it refills itself forever; none of it comes back. This is the one path needing permission: being the token’s current fee recipient, which is not the same as having launched it.