The Builder Base is a separate economy
Your Builder Base runs on its own resources — Builder Gold and Builder Elixir — which are completely separate from your Home Village gold and elixir. They have their own storages, their own collectors, and they come mostly from winning versus battles rather than from raiding for loot. Builder Gold funds your Builder Hall defenses and wall segments; Builder Elixir funds Builder Base troops and Star Laboratory upgrades. This service farms both so your Builder Hall upgrades never sit idle waiting on a win streak.